It’s common knowledge that excess body weight contributes to a variety of health problems that reduce life expectancy: increased blood pressure; raised levels of cholesterol and insulin; and reduced immunity against debilitating diseases such as dementia, arthritis, diabetes, cancer, and heart disease.
Unfortunately, many people struggle to maintain a healthy weight and protect themselves from these health risks. This is due in large part to the amount of conflicting advice about what type of diet we should follow to stay in shape.
(Shortform note: Globally, 13% of adults are obese, while 39% of adults and 20% of children and adolescents are overweight. Research confirms that obese individuals are more likely to suffer from health problems that lead to premature death. Statistics from 2017 reveal that 8% of the global population (4.7 million people) died prematurely as a result of obesity. However, while there’s a clear correlation between obesity rates and premature death rates, these statistics don’t account for other lifestyle factors, such as whether, in addition to being obese, an individual smoked or drank excessive alcohol. Therefore, it isn’t clear exactly how many premature deaths are due solely to excess weight, and how many to a combination of unhealthy lifestyle choices.)
In How Not to Diet, Michael Greger, physician and best-selling author of How Not to Die, adds a much-needed voice of clarity to the world of weight loss. He draws on extensive scientific research to explore the healthiest and most efficient way to lose weight and keep it off.
This guide explores Greger’s research in three parts:
Before you can lose weight or maintain your current weight, you first need to understand the factors that lead to unintentional weight gain. This knowledge will help you make informed decisions about how to achieve and maintain your ideal weight.
People often blame various factors for unintentional weight gain, such as a sedentary lifestyle, insufficient motivation to stick to a healthy routine, low metabolism, or “fat genes.” However, according to Greger’s research, there’s only one factor that determines whether you put on weight: your calorie intake—the number of calories you consume and what form they take.
(Shortform note: While Greger’s explanation for weight gain may appear reductive to some, research confirms that it really is that simple. John Walker (The Hacker’s Diet) explains that your body needs energy—measured in calories—to function. If you eat the exact number of calories your body needs to function, you do not gain weight—even if your diet consists of foods high in fat and sugar. However, maintaining a healthy weight may seem more complicated than this because the number of calories you burn each day does depend on various factors, such as your activity level, your metabolism, and your genetics.)
In this part of the guide, we’ll discuss the type of calorie intake that leads to excess body weight. We’ll first explain why we’re naturally inclined to crave high-calorie foods. Then we’ll clarify how eating certain types of food—those that are high in calories and low in nutrition—contributes to weight gain.
Greger argues that the first reason we’re prone to weight gain is that we’re naturally inclined to seek out calorie-dense foods—foods that contain a high number of calories per gram. For example, a gram of butter contains more calories than a gram of flour, which makes the butter more calorie-dense than, therefore preferable to, flour.
He explains that this is because our bodies evolved within an environment of scarcity—we lived in the wild and only ate what we were able to hunt or gather. Since food wasn’t always available, we developed an instinctual preference for calorie-dense foods. The faster we satisfied our caloric needs, the less effort we had to put into hunting and gathering our food. For example, hunting, butchering, and preparing deer meat would take you a few hours of effort but would result in substantially more calories than you’d collect from foraging berries in that same amount of time. Therefore, you’d be more inclined to hunt and eat deer meat than forage for berries.
Additionally, consuming high-calorie foods ensured our survival because it allowed our bodies to store excess calories as fat reserves to fall back on in times of famine.
Our environment has evolved over time, and high-calorie foods are now readily available: Instead of eating only what we can hunt or gather, we go to the store and choose what we want to eat. However, Greger argues, our bodies have not evolved, so we still crave high-calorie foods. This means that we’re constantly tempted to gorge on more calories than we need. Each time we do, our bodies store these excess calories as body fat. But, because we’re no longer afflicted with food shortages, our bodies never get the opportunity to use these fat reserves—resulting in a continual accumulation of fat.
Some of Us Are More Genetically Predisposed to Store Fat Than Others
Many authors mirror Greger’s claim that, thanks to evolution, we’re hardwired to crave high-calorie foods and store excess calories as fat. Some notable proponents of this theory include James Clear (Atomic Habits), Glenn Livingston (Never Binge Again), Neil Shubin (Your Inner Fish), and John Walker (The Hacker’s Diet).
However, while this theory clarifies why we crave high-calorie foods, it doesn’t explain why some individuals can consume excess calories without putting on weight while others store all excess calories as fat. Researchers explain that not all of our ancestors adapted to the environment in the same way—some developed the ability to store more fat reserves than others and passed on this tendency to their offspring. This tendency continues to pass from generation to generation. As a result, some of us are genetically predisposed to store fat while others aren’t.
In light of this research, pharmaceutical companies are examining the genetic similarities among obese individuals. This knowledge may help them develop new drug strategies to prevent or treat weight gain and counter the rising rates of obesity.
Greger argues that the second reason we’re prone to weight gain is that the food industry takes advantage of our instinctual preference for calorie-dense foods. It does this by encouraging us to eat processed foods and animal-derived products such as meat, fish, and dairy, which are cheap to produce and distribute.
These food groups directly contribute to weight gain because they lack nutrition and are high in calories. Greger explains that the food industry strips crops of all nutritional value and fiber by either running them through processing mills or feeding them to livestock to create animal-derived products (such as meat, dairy, and eggs). It then adds high-calorie, low-nutrition components such as sugar or salt, oil, preservatives, artificial colorings, and flavorings to create fatty, starchy, sugary, or salty products.
(Shortform note: Michael Pollan (In Defense of Food) expands on how the food industry’s focus on profit promotes weight gain. To maximize profits, food companies focus on producing quantity rather than quality. One way they achieve this is by breeding certain types of food sources for higher yields, such as seeds and livestock. For example, wheat is bred to increase its yield output, and Holstein cows are bred to produce more milk. But manipulating the production of food in this way reduces its nutritional value. Wheat contains 28% less iron than before, and milk from Holstein cows has less butter fat and fewer nutrients than milk from other cow species. As a result, we need to eat more food—which results in more calories—to gain the same level of nutrients that less food provided in the past.)
According to Greger, eating these foods creates four negative consequences that lead to weight gain:
Let’s explore these four negative consequences in more detail.
According to Greger, because processed foods and animal products contain calories in their simplest form (fat and sugar), your body doesn’t have to work hard to digest them because there aren’t many nutrients to extract. As a result, you don’t burn many calories digesting the food. When you continually eat these foods, your body gets used to applying less effort to digest your food. It adapts by decreasing your metabolism—the rate at which your body burns calories and fat reserves. This slows down your ability to burn through any excess calories you’ve consumed.
(Shortform note: Health professionals offer differing opinions about the relationship between digestion and metabolism. While they all validate Greger’s argument that calorie-dense foods require less effort to digest (thus burning fewer calories), some experts argue that metabolic rates remain steady from age 20 to 60 despite what you eat. They claim that metabolism can fluctuate during this time if body fat and muscle mass percentages change: The more body fat you accumulate, the lower your metabolism. The more muscle mass you gain, the higher your metabolism. This implies that consuming calorie-dense foods may indirectly decrease metabolism—because it increases body fat percentages.)
Greger argues that processed foods and animal products increase your appetite in four ways:
1) They quickly leave your stomach: Greger explains that food remains in your stomach until the digestive process, which involves extracting and sorting through any nutrients in the food before excretion, is complete. During this time, your body releases a steady supply of nutrients from the food in your stomach into your bloodstream, creating hormonal changes that make you feel full. However, since processed and animal-derived high-calorie foods are devoid of nutrition and don’t take long to digest, they don’t sit in your stomach for long or provide sufficient nutrients to satiate you.
(Shortform note: Dieticians clarify how quickly processed foods leave your stomach. Nutritionally complex food (such as fiber, protein, and complex carbohydrates) takes your small intestine an average of two hours to process. Since processed foods and animal-derived products aren’t nutritionally complex—because they’re generally composed of simple carbohydrates and fats in their purest form—the small intestine can extract any nutritional content in approximately 30 to 60 minutes. Therefore, as Greger says, these foods don’t keep you full for long.)
2) They trigger blood sugar spikes: According to Greger, the more quickly your body digests food, the more sugar it releases into your bloodstream—creating spikes in your blood sugar levels. This blood sugar spike creates hormonal changes that trigger your appetite. He notes that these blood sugar spikes occur more after eating foods containing high amounts of saturated fats—such as meat and fish—which causes an excessive release of insulin.
(Shortform note: Diabetes research backs up Greger’s claim that quick digestion and saturated fats contribute to blood sugar spikes that increase appetite because they trigger your liver to release more glucose into your bloodstream. However, your diet’s not the only factor that contributes to blood sugar spikes—menstrual cycles, illnesses and injuries, hormonal changes, adrenaline rushes, and anaerobic exercise can also produce the same effect.)
3) They encourage cravings: Greger claims that foods that contain concentrated forms of salt, sugar, fat, and artificial additives initiate the release of hormones that trigger cravings. This means that eating these foods encourages your body to crave even more of them, regardless of how full you are.
(Shortform note: Neurochemical research sheds light on how these ingredients stimulate your hormones to encourage cravings. Foods that contain salt, sugar, and fat are more likely to trigger cravings because, in addition to having an innate tendency to seek high-calorie foods, you also have an innate tendency to seek gratification. The flavors of these ingredients gratify you by stimulating the production of pleasurable neurochemicals in your brain. As Greger says, because food companies are aware of these two tendencies, they intentionally pump high-calorie foods full of salt, sugar, and fat to fuel your cravings and encourage you to consume more.)
4) They don’t nourish you: Greger explains that, because these foods are devoid of nutrition, eating them doesn’t satisfy your nutritional needs. Since your body lacks nutrition, it adopts two defensive measures: First, to prevent starvation, it reduces the number of calories it burns digesting food so that it can store more of these calories as fat reserves. Second, it induces cravings for high-calorie foods in an attempt to satisfy its nutritional needs. This leads you to eat more calories than your body can burn.
(Shortform note: Greger implies that eating foods that are calorie-dense and low in nutrition pushes the body to adopt these defensive measures. Dieticians clarify that this isn’t the case: The body only adopts these two defensive measures when it suffers from extreme malnourishment—for instance, when someone suffers from an eating disorder and starves their body of nutrition. Starving the body this way decreases muscle mass, which then lowers metabolism. (Recall: the higher your muscle mass, the higher your metabolism.) When your metabolism decreases, you feel more lethargic—leading you to crave foods that will provide a boost of energy.)
An Overview of the Digestive Process
Throughout these four points, Greger argues that the way you digest processed foods and animal-derived products increases your appetite. We’ll clarify his argument with an in-depth explanation of the digestive process.
Nutrients in food provide the cells in your body with the fuel they need to function. Before your cells can access these nutrients, your body must first digest food into molecules that it can absorb into your bloodstream.
1) The digestive process begins in your mouth before you even taste your food. As soon as you think about, see, or smell appetizing food, you start salivating. This saliva contains a digestive enzyme (amylase) that helps break down any starch or sugar in your food.
2) When you chew your food, your saliva moistens it to help you swallow it. The digestive enzymes in your saliva begin breaking down any starch before the food leaves your mouth. This food then moves down into your throat and through a muscular tube (the esophagus). Waves of muscle contractions force the food down through this tube into your stomach.
3) Your stomach muscles then churn and mix the food with digestive juices comprised of acids and enzymes, breaking it into small pieces. This food doesn’t leave your stomach until it’s been processed into a thick liquid (chyme) that’s the right consistency to move into your small intestine.
4) With the help of your liver, gallbladder, and pancreas, your small intestine breaks this chyme down into molecules that it supplies to your bloodstream to feed your cells. This process involves extracting calories and breaking down:
Protein into amino acids (4 calories per gram)
Starches into simple sugars (4 calories per gram)
Fats into fatty acids and glycerol (9 calories per gram)
Once all the food’s nutrients have been absorbed into your bloodstream, undigested matter travels to the large intestine.
5) Your large intestine separates the water from this matter and converts it to solid waste that moves through your colon to your rectum, where it waits until you have a bowel movement.
According to Greger, processed foods and animal products stimulate inflammation within the body. He explains that, normally, inflammation is the body’s way of triggering the healing process whenever it gets hurt or sick. In this type of situation, the inflammation that occurs is short-term and targeted toward resolving a specific problem. For example, you stub your toe, and it looks and feels inflamed for a few hours until it heals.
However, processed foods and animal products contain high quantities of saturated fat and trans fat—substances that stimulate an inflammatory response that is long-term and unspecific. This means that the inflammation lingers in your whole body and, instead of healing you, it creates hormone imbalances that perpetuate many diseases such as heart disease, bowel disease, arthritis, and dementia. In addition to harming your health, these hormone imbalances contribute to weight gain because they raise your blood sugar levels, increase your appetite, and decrease your metabolism.
Chronic Inflammation Attacks Healthy Cells, Tissues, and Organs
Research confirms that processed foods and animal-derived products (particularly dairy and red meat) contribute to chronic inflammatory diseases and weight gain. Additionally, people who regularly eat these foods are at twice the risk of developing colorectal cancer, and they up their risk of mortality by 23%.
These foods cause inflammation, disease, and weight gain because they contain unnatural substances that your body classifies as threats to your immune system. To protect itself, it produces and sends out inflammatory cells to trap and neutralize these threats.
The more inflammatory foods you consume, the more inflammatory cells your body releases in response. These inflammatory cells build up and eventually start attacking healthy cells, tissues, and organs, resulting in diseases like diabetes, rheumatoid arthritis, and heart disease. In other words, your body’s attempts to protect your immune system actually weaken it. To compensate for this weakness, your body funnels even more resources toward protecting your immune system. As a result, it spends less energy digesting food—contributing to a decrease in metabolism and an increase in blood sugar levels and appetite.
Greger argues that processed foods and animal products expose your body to chemicals that promote weight gain, such as organotins, BPA, and phthalates. He explains that, normally, the total number of fat cells in your body remains stable—when you gain or lose weight, these cells just enlarge or shrink. However, exposure to these chemicals creates hormonal imbalances that disrupt this stability. These imbalances activate the creation of new fat cells—by converting tissue stem cells into fat cells—and expand the size of existing fat cells.
While chemical pollutants get into our food via several sources in the processed food supply chain—such as plastic packaging—much of our food is contaminated before it’s packaged. This is because there are chemical pollutants both in the pesticides used to farm the crops that make our food and in the artificial additives used to make processed food more palatable.
Notably, Greger claims that 90% of chemical pollutant exposure comes from eating animal-derived foods (both organic and non-organic) such as meat, fish, and poultry—because, in addition to feeding these animals contaminated crops, livestock owners pump them full of artificial growth-enhancing hormones.
(Shortform note: Greger bases his claim that 90% of all chemical pollutant exposure comes from eating animal-derived foods on a study (1992-2022) that examined the correlation between organic pollutants and diabetes. The trial included 2,016 participants. More recent research from the Environmental Protection Agency clarifies that over 90% of exposure to a specific type of chemical (dioxin) does come from eating animal-derived foods.)
The Possible Effects of Chemical Pollutant Exposure and How to Avoid Them
Research on how organotins, BPA, and phthalates impact weight gain is still in the preliminary stages—the effects Greger discusses here are largely based on animal studies that haven’t yet been verified by human trials.
However, preliminary findings back up the theory that chemical pollutant exposure contributes to excess body weight. These studies speculate that these chemicals might interfere with your endocrine system. Because the endocrine system helps regulate metabolism and body weight, exposure to these chemicals may:
Alter the rate of fat cell production versus destruction, favoring an increase in the number of fat cells you produce and store
Shift energy balance, gut microbiota, and metabolism to favor calorie storage
Modify hormonal control of appetite and satiety levels
There are approximately 1,000 different chemicals that may produce these effects. In addition to pesticides, packaging, and artificial additives and hormones, they’re present in everyday household items like food containers, toys, personal care products, and cleaning supplies. Since they’re present in such a wide range of sources, they contaminate our food, water, and air—making it impossible to avoid them entirely.
However, even though you can’t entirely avoid them, there are ways to reduce your exposure:
Opt for organic produce and personal care products.
Store food and beverages in stainless steel, aluminum, or glass containers.
Avoid heating foods in plastic containers.
Now that you understand why you crave high-calorie foods and how eating processed foods and animal products contributes to weight gain, let’s discuss why adopting a plant-based diet is the healthiest and most effective way to maintain a healthy weight.
A plant-based diet includes whole grains, legumes, fruits, and vegetables. It excludes processed foods and animal-derived products such as meat, fish, eggs, and dairy. Because it omits foods that are calorie-dense (high in fat, sugar or salt, and starch), it’s naturally high in nutritional value and low in calories. This means that you can eat as much of these foods as you want without having to restrict portion sizes—which makes this diet both healthy and easy to stick to.
(Shortform note: While nutritionists validate Greger’s claim that a plant-based diet is low enough in calories that you don’t have to restrict portion sizes, they do warn that it could lead to nutritional deficiencies and major health problems. This is because plant-based diets lack B12 and are low in heme iron, calcium, iodine, and DHA. Therefore, before adopting this diet, plan out how you’ll fulfill your nutritional needs by adding supplements or specific ingredients. This will help you maintain your weight and keep you in good health.)
Greger explains that plant-based foods have two positive effects that allow you to eat as much as you want and maintain a healthy weight:
Let’s explore these two positive effects in more detail.
The first reason plant-based foods help maintain a healthy weight is that they contain plenty of fiber. According to Greger, fibrous foods reduce both the number of calories your body stores as fat and the number of calories you consume. Let’s explore these two effects in detail.
According to Greger, fibrous foods reduce the number of calories your body stores as fat. This is because fibrous plants have tough outer layers that are difficult to digest. This means that your body can’t break these foods down and digest all of the calories before you excrete them.
Further, fibrous foods reduce the number of calories you extract from accompanying foods: As fiber passes through your body, it mixes with and encases other foods in your digestive tract. Because this casing is indigestible, it traps the calories in these other foods and prevents them from being extracted by your body before you excrete them.
For example, people who eat whole wheat pasta (high in fiber) with a cream sauce would excrete more calories from the cream sauce than those who pair the sauce with white pasta (low in fiber). This is because the fiber in the whole wheat pasta envelops the calories in the sauce and prevents them from being digested by your body.
The Difference Between Soluble Fiber and Insoluble Fiber
Research expands on how fibrous foods help prevent weight gain by explaining that most plants contain two types of fiber: soluble and insoluble. Though both types are indigestible, they help maintain a healthy weight in different ways.
Soluble fiber (two calories per gram) dissolves in bodily fluids to form a thick gelatinous substance that passes through your digestive tract. As Greger says, it encases other foods and prevents your body from extracting calories from them. Additionally, it encases fat and cholesterol—which means you excrete these substances instead of absorbing them. Sources of soluble fiber include apples, barley, beans, carrots, citrus fruits, oats, and peas.
Insoluble fiber (zero calories per gram) doesn’t dissolve in fluids. Instead, it absorbs fluids and sticks to other foods, forming bulkier stools that help keep you regular. Sources of insoluble fiber include beans, nuts, wheat bran, whole wheat flour, cauliflower, green beans, potatoes, and berries.
The recommended daily intake of fiber for people under the age of 50 is 25 grams for women and 38 grams for men, a quarter of which should come from soluble fiber.
Greger claims that fibrous foods also reduce the number of calories you consume in the first place. This is due to two reasons:
1) They require more chewing: This means they take longer to eat than processed foods. According to Greger, the more you chew, taste, and keep food in your mouth, the more satiated you feel, even if the food’s low in calories. This feeling satisfies your cravings for high-calorie foods and inhibits the tendency to reach for additional helpings.
(Shortform note: Multiple studies verify that chewing more leads to eating less during a particular meal. However, while Greger focuses on how chewing food during a meal reduces the amount you eat at that meal, studies reveal that chewing something tasteless, such as flavorless gum, before meals reduces appetite and prevents compulsive eating. This is because chewing tricks your brain into believing that you’re consuming real food and satiating your appetite. Because you believe that you’re already consuming food and filling up, you pay less attention to real food—which means you don’t crave foods that lead to compulsive eating.)
2) They require more effort to digest: As we’ve discussed, food remains in your stomach until the digestive process is complete. Greger explains that, since plant-based food takes a long time to digest, it makes you feel satiated for longer. This is both because your stomach is full for a longer period of time and because, during this time, it releases a steady supply of nutrients into your bloodstream.
(Shortform note: Fiber has long been known to satiate appetite and keep us full for longer. While previous research put this down solely to Greger’s two reasons—that fibrous foods take longer to chew and digest—recent studies reveal that there’s more going on beneath the surface. Digesting fiber releases an anti-appetite molecule (acetate) into the bloodstream, where it travels to and accumulates in the hypothalamus—a part of the brain that regulates hunger. Once there, it spurs chemical reactions that favor appetite suppression.)
The second reason plant-based foods help maintain a healthy weight is that, in addition to fiber and other nutritional content, fruits and vegetables are mostly full of water.
Greger explains that consuming foods with high water content fills you up more than just drinking water does. This is because water is trapped within the structure of these foods—which means your body requires more time and effort to separate the water from the food, and therefore burns more calories. (Recall: The longer it takes to digest food, the more calories you burn.) As a result, eating these foods naturally increases your metabolism and helps you burn calories and fat reserves more quickly.
Further, because water-rich foods take longer to digest, they sit in your stomach for longer, making you feel full for longer. Since water has zero calories, Greger emphasizes, these foods fill you up without adding to your calorie count.
(Shortform note: In addition to increasing your metabolism and filling you up, consuming water-rich foods provides two benefits over simply drinking water: It helps you absorb more nutrients and hydrates your body more effectively. Regular water intake is essential because the body is unable to store a reservoir of water. Since your body can’t store water, any water you drink quickly passes through your digestive tract—which means it doesn’t hydrate you for long. Along the way, it also flushes nutrients out of your body before you get a chance to digest them. However, consuming water-rich foods helps your body absorb water and any accompanying nutrients more slowly—thus providing hydration and nutrition more effectively.)
Now that you understand why eating plant-based foods helps maintain a healthy weight, let’s discuss how to adapt this diet to accelerate weight loss. Greger suggests four dietary changes to achieve this:
Let’s explore each of these four methods in detail.
Aim to eat your largest meal in the morning, and your smallest meal in the evening. Greger explains that the amount of time and effort your body spends digesting food decreases during the day. This means that you burn more calories digesting food in the morning than you do in the evening. Therefore, eating more food earlier in the day reduces the overall number of calories your body stores as fat throughout the day.
Since metabolic rates hinge on multiple factors, Greger doesn’t define exactly how many more calories you burn in the morning. However, we’ll provide a hypothetical example to illustrate how this principle works.
Let’s say that, during digestion, you burn half the calories of the food you eat in the morning compared to a quarter of the calories of the food you eat in the evening. If you consume 1,000 calories during the day, the number of calories you burn or store as fat would differ depending on when you ate your largest meal.
If you consumed 750 calories in the morning and 250 calories in the evening, you would burn 437.5 calories and store 562.5 as fat: (750 ÷ 2) + (250 ÷ 4) = 437.5 calories burned. 1,000 - 437.5 = 562.5 calories stored.
However, if you consumed 250 calories in the morning and 750 calories in the evening, you would burn 312.5 calories and store 687.5 as fat: (250 ÷ 2) + (750 ÷ 4) = 312.5 calories burned. 1,000 - 312.5 = 687.5 calories stored.
(Shortform note: While research backs up the claim that early meals contribute to weight loss, it offers a different theory to explain it. Studies reveal that people who eat most of their daily calories in the morning don’t burn more calories than those who eat more in the evening. However, people who eat a large breakfast do report feeling less hungry during the day and don’t feel the urge to snack between meals. Therefore, because consuming a large breakfast helps keep calorie intake in check, it can contribute to weight loss.)
As we’ve previously discussed, fiber reduces both your appetite and the number of calories your body digests. However, Greger argues, 97% of Americans fall far short of the recommended minimum daily amount. (Shortform note: Recall that the recommended daily intake for people under the age of 50 is 25 grams for women and 38 grams for men.) He suggests that you can easily up your fiber intake by replacing white foods with whole grain equivalents (for example, replacing processed white pasta with whole wheat pasta) and adding root vegetables and legumes such as chickpeas, lentils, and black beans to your diet.
(Shortform note: Research validates Greger’s claim that most Americans fall short of the recommended minimum daily amount of fiber. However, while there’s no disputing that consuming more fiber helps you lose or maintain weight, proceed with caution: Gradually introduce fibrous foods into your diet. Research reveals that dramatically increasing your daily intake can cause adverse side effects. These effects include bloating, abdominal pain, flatulence, diarrhea, constipation, and temporary weight gain. It can also create complications for people with Crohn’s disease or diabetes.)
Greger suggests that, in addition to staying hydrated throughout the day, you should drink water before each meal. This is because any water you drink sits in your stomach for a short while, during which time it makes you feel full. Additionally, eat water-rich foods such as fruits, vegetables, soups, or salads as a starter. The water you drink or consume will satiate you and reduce your appetite for the main meal. As a result, you’ll consume fewer calories overall.
How Keeping Hydrated Contributes to Weight Loss
We’ve already explained why consuming water-rich foods helps you lose or maintain weight—because it fills you up, increases your metabolism, helps you absorb more nutrients, and hydrates your body. But, we haven’t yet explored how keeping hydrated helps you lose weight.
Though many studies show a positive correlation between increased water consumption and weight loss, researchers are still unsure about why it’s so effective. They offer five possible reasons:
1) It suppresses appetite: As Greger says, liquids take up space in the stomach, creating a feeling of fullness that reduces appetite. The following list breaks down how long different types of liquids remain in your stomach:
Plain water: 10 to 20 minutes
Simple liquids (juice, tea, and soda): 20 to 40 minutes
Complex liquids (smoothies and protein shakes): 40 to 60 minutes
2) It curbs unnecessary calorie consumption: People often confuse feeling thirsty with feeling hungry, which leads them to consume more food than they need.
3) It helps you burn more calories: The body expends more energy heating up cold water in preparation for digestion.
4) It removes waste from your body: Water helps filter toxins, prevents constipation, and reduces bloating and swelling—factors that can add extra pounds to your weight.
5) It helps metabolize fat: The body needs water to effectively metabolize fats and carbohydrates in the digestive tract as well as the fats it has stored.
Gregers suggests that you drink three cups of green tea each day, and add the following ingredients to your food: turmeric, ginger, garlic, nutritional yeast, vinegar, black cumin, and cayenne pepper. These ingredients are high in anti-inflammatory properties. (Recall: Inflammation creates hormone imbalances that increase blood sugar levels and appetite.) This means that consuming anti-inflammatory ingredients prevents blood sugar spikes, regulates appetite, and boosts metabolism.
Possible Side Effects of Consuming Anti-Inflammatory Ingredients
Research in this area isn’t definitive—while ongoing studies suggest that consuming these ingredients might prevent blood sugar spikes, regulate appetite, and boost metabolism, they also reveal numerous possible side effects to consider before adding them to your diet:
People with severe caffeine sensitivities may experience insomnia, anxiety, irritability, nausea, or an upset stomach.
Consuming the tea alongside stimulant drugs may increase blood pressure and heart rate.
It stimulates the production of gastric acid, which can lead to an upset stomach.
It thins the blood—making it unsafe for pregnant women or people who take blood-thinning drugs.
Large doses (more than five grams a day) may cause gas, heartburn, an upset stomach, or mouth irritation.
It might be unsafe for people who take blood-thinning drugs or medication for diabetes or high blood pressure.
Excess consumption can trigger migraines and cause dizziness, nausea, vomiting, heartburn, diarrhea, gastroesophageal reflux disease, swelling in the kidneys, and liver toxicity.
It may lead to bad breath, excess sweating, vaginal yeast infections, and skin irritations such as eczema or rashes.
It might be unsafe for people who take blood-thinning drugs or medication for high blood pressure.
It can cause gas or an upset stomach.
Possible allergic reactions include hives and asthma.
It might be unsafe for people with Crohn’s disease; elevated yeast antibody counts; or an autoimmune disease such as rheumatoid arthritis, lupus, or multiple sclerosis.
Because it’s highly acidic, it can cause acid burns and injury to the digestive tract (the throat, esophagus, and stomach) resulting in ulcers, gastritis, vitamin deficiencies, and an increased risk of developing cancer of the upper gastrointestinal tract.
It damages the liver and kidneys, irritates the central nervous system, and may decrease potassium levels and bone density.
It can cause hypoglycemia, creating symptoms such as anxiety or dizziness.
It may weaken tooth enamel, leading to cavities and other dental problems.
Due to its tyramine levels, it may cause high blood pressure, joint pain, urticaria, IBS, and headaches.
It might be unsafe for people who take blood-thinning drugs, laxatives, diuretics, or medications for diabetes or heart disease.
It may cause nausea and bloating.
Due to limited research on its side effects, women who are pregnant or breastfeeding should only use small amounts for flavoring food.
It might be unsafe for people with kidney problems or those who take blood-thinning drugs or beta-blockers.
In addition to causing irritability to the throat, mouth, and nose, it may lead to heartburn, stomach disorders, nausea or vomiting, and bronchitis.
It aggravates IBS and gastroesophageal reflux disease symptoms.
Possible allergic reactions include eczema, swelling, coughing, urticaria, and conjunctivitis.
It might be unsafe for people who take blood-thinning drugs, ACE inhibitors, and antacids.
Greger argues that adopting a plant-based diet helps to achieve and maintain a healthy weight. In this exercise, consider how you might implement his advice.
Consider what you eat. Recall Greger’s explanation of what causes weight gain—processed foods and animal products—and list anything in your regular diet that might lead to unintentional weight gain. (For example, maybe you eat candy, white bread, or ham.)
Pick an item on your list and write down at least one plant-based substitute for it. (For example, you might replace candy with carrot sticks, or white bread with whole wheat bread.)
Consider when you consume your calories. Recall Greger’s explanation of how the amount of time and effort your body spends digesting food decreases during the day, and write a brief reflection on when you tend to eat most of your calories. (For example, perhaps you skip breakfast, eat a small lunch, and eat high-calorie snacks before eating a large dinner.)
Recall Greger’s advice to eat your largest meal in the morning and your smallest meal in the evening. List one way you could adapt your schedule to accommodate this. (For example, you might wake up half an hour earlier to make time for a large breakfast, or plan your daily meals in advance so that you don’t end up reaching for high-calorie foods in the evening.)