Lose Weight by Eating the Right Food (Supported by Science)

1. Choose Quality Calories

Research shows that most people who change how much they eat without changing what they eat regain all of their lost weight - or worse, end up gaining more than they lost. Why is it not surprising? Because we can all lose weight; losing weight by creating a calorie deficit is not hard. What's hard is maintaining the weight loss.

The problem with losing weight by creating a calorie deficit is that it disrupts your hormonal balance. (1) That means that your metabolic hormones, such as ghrelin, insulin, leptin, thyroid, and others shift in a way that causes increased hunger and cravings, and slowed metabolism. And unless you don't mind being hungry for the rest of your life, fighting your biology is useless. The key to a long-term weight loss is choosing high quality foods and adopting a lifestyle that will balance your hormones and restore your body's natural ability to stay at its best weight.

Rather than choosing foods based only on caloric value, opt for unrefined and minimally processed foods high in water, fiber, protein, and healthy fats. These foods will fill you up quickly and help you stay full longer. Center your diet around vegetables, low-sugar fruits, legumes, nuts and seeds, and lean meats. Avoid low-quality processed foods including refined (white) grains, sugar and artificial sweeteners, fried foods, foods high in saturated and trans fat, and high-glycemic foods.

2. Load up on High-Fiber Food

Fiber is a carbohydrate found in whole plant foods. Because your body can't digest fiber, it passes quickly through the digestive track without causing blood sugar spikes. Dietary fiber also reduces the risk of heart disease, type II diabetes, some cancers, diverticular disease, constipation, and is beneficial for weight loss. (2, 3) While fiber doesn't have any fat-burning properties, it has appetite-suppressant qualities which help to prolong the feeling of satiety and reduce calorie consumption.

There are two types of fiber: soluble (viscous) and insoluble (non-viscous). Soluble fiber dissolves in water when it reaches the gut and has numerous beneficial effects on metabolism. It is made up of compounds such as beta-glucans, mucilages, pectins, gums, psyllium, and some hemicelluloses. Soluble fiber is found predominantly in fruits, vegetables, nuts, beans, and oats. Insoluble fiber, on the other hand, doesn't dissolve in water and acts mainly as a bulking agent. It is made up of compounds such as cellulose, lignin, and some hemicelluloses. Most of insoluble fibers come from the bran layers of cereal grains.

Fiber promotes weight loss by:

Suppressing Appetite

Both soluble and insoluble fiber is beneficial for health, but only the soluble type seems to have the appetite-suppressant effect. (4) The reason is that soluble fiber dissolves into a gel-like substance when reaching the gut by attracting water. This gel-like substance slows down the emptying of the stomach and increases the time it takes to digest and absorb nutrients, resulting in a notably suppressed appetite and increased satiety. There is also some evidence that eating foods high in soluble fiber helps to target belly fat specifically. (5)

Feeding Friendly Bacteria in the Gut

The human gut is home to approximately one hundred trillion bacteria. (6) According to research, gut flora plays a major role not only in gastro-intestinal function, but also in weight management. (7) Lean people tend to have various amounts of healthy bacteria compared to obese people. One study found that obese individuals were able to reduce their abdominal fat by 5% and their subcutaneous fat by more than 3% just by drinking a probiotic-rich fermented beverage for 12 weeks. (8) The precise way in which gut bacteria positively affect weight loss is still under debate.

The recommended amount of fiber per day is related to the number of calories eaten during the day. For healthy adults, the USDA recommends 14 grams of fiber per 1000 calories. (9) If you want to increase the amount of fiber in your diet, you can also use a fiber supplement. The only type of fiber supplement that seems to cause weight loss is glucomannan. (10) However, keep in mind that getting your fiber from whole plant foods is the best. It's the combination of all the nutrients in various foods that provides the most benefits.

3. Eat More Protein

Making protein a part of your every meal is another important piece in weight loss. According to research, quality protein is important not only for weight loss and metabolic health (11), but also for increasing muscle mass (12) preventing muscle loss during weight loss (13), lowering blood pressure (14), and for healthy bones (15).

There are two different sources of protein: plant and animal. Plant-based protein is generally better for weight loss because it offers more fiber, MUFAs (MonoUnsaturated Fatty Acids), phytonutrients, and contains less saturated fat. Some great choices include beans, chickpeas, lentils, peas, nuts and seeds, and soy. However, animal protein offers some benefits as well. What sets animal-based protein apart from plant-based protein is its essential amino acids content. Essential amino acids  have to come from food; your body cannot make them. All animal-based protein is complete (it contains all nine essential amino acids) while plant-based protein, with the exception of soy, lacks at least one amino acid. That being said, most dietitians believe that plant-based diets contain such a wide variety of amino acids that vegans should have no problem getting all of their amino acids with very little effort. (16)

Protein contributes to weight loss by:

Increasing Thermogenesis

The thermic effect refers to the energy used to digest, absorb, and transport the food's nutrients to your body's cells. Protein has a higher thermic effect (25 – 30%) than carbohydrates (6 – 8%) or fats (2 – 3%). (17) This means that your body burns more calories processing protein than processing carbohydrates or fat. As discussed in an article by Authority Nutrition, 100 calories of protein would end up 75 calories, while 100 calories of fat would end up as 98 calories. (18)

Suppressing Appetite

It takes twice as long to digest protein than it takes to digest carbohydrates. A longer digestion time means that you feel full longer without your energy crashing. Eating one serving of beans, chickpeas, lentils, or peas per day increases fullness and leads to better weight management and weight loss. For the same amount of calories, protein is a much better choice than carbohydrates when you want to lose weight.

Increasing Satiety (Reducing Cravings)

Protein increases satiety more than carbohydrates or fats and may facilitate a reduction in energy consumption. It remains unknown how exactly protein increases satiety. According to research, the protein-induced satiety could not be explained by changes in the hunger hormone ghrelin or in the satiety hormone leptin. (19)

4. Don't Be Afraid of Healthy Fats

Consumption of fat has frequently been blamed for the rise of obesity. However, research investigating the link between high dietary fat intake and weight gain has been inconsistent. (20) In fact, studies suggest that to lose fat, you actually need to eat healthy fat. Yes, there is such a thing as healthy fat! The best fat for weight loss, especially abdominal weight loss, appears to be MUFAs (MonoUnsaturated Fatty Acids). MUFAs are plant-based fats found in oils, olives, nuts and seeds, avocados, and dark chocolate. Not only do these fats target belly fat, but they also enhance heart health, reduce chronic disease, lower risk of breast cancer, benefit insulin and blood sugar control, and reduce inflammation. (21, 22, 23)

MUFAs contribute to weight loss by:

Suppressing Appetite

One of the great benefits of eating fat is its satiating effect. Fat reduces hunger and impairs food intake by setting off satiety signals when it reaches the small intestine. These signals are triggered by the release of gut hormones cholecystokinin (CCK) and peptide YY. (24, 25) The satiating effect of fat is dependent on two properties: fatty acid chain length - the longer the chain, the greater reduction of hunger and food intake - and the degree of fatty acid saturation - unsaturated fatty acids induce a greater reduction in food intake than saturated fatty acids.

Burning Fat

Another hormone important in weight loss is a fat-burning hormone adiponectin. Adiponectin, same as leptin, is released by the fat cells and communicates with the brain when the right amount of food has been consumed. Consuming foods containing MUFAs helps to keep adiponectin levels high and promote weight loss. (26) High levels of adiponectin are associated with boosting metabolism, burning fat, increasing insulin sensitivity, and reducing appetite. Low adiponectin levels, on the other hand, are prevalent in obesity. (27)

5. Quit Sugar, Especially Fructose

High intake of sugar and sugar-sweetened beverages leads to obesity. Sugar (sucrose) is a disaccharide made up of two simple sugar molecules - glucose and fructose. Although high consumption of sugar is never recommended, research suggests that fructose in particular is associated with abdominal obesity. (28)

Fortunately, humans rarely consume fructose alone. Fructose is present together with equivalent glucose in almost every food, including both natural sources and added sugars. (29) However, it's very easy to consume high amounts of loose fructose on a daily basis because it's the sweetener both consumers and cooks prefer. As a result, fructose is "added not just to sodas, energy drinks, and sports drinks favored by adolescents and adults but also to juice drinks consumed by infants and toddlers and to snacks, processed meats, sauces, and many other foods consumed by people of all ages." (30)

Fortunately, fructose found in whole fruits – full of fiber, water, vitamins, minerals, antioxidants, and phytonutrients – doesn't have the same detrimental effect on health as loose fructose. Fructose found in whole fruits hits the liver slowly and in small amounts. (37)

Fructose causes weight gain by:

Being Metabolized into Fat

The metabolic burden of fructose rests predominantly on the liver (anywhere from 90% - 100%). (29) However, the liver can only store small amounts of glucose as glycogen. If the liver gets flooded with high quantities of fructose, it turns it into fat. (31) Glucose, on the other hand, is used by every cell in the body and only 20% by the liver. About 80% of glucose is absorbed by the body for immediate energy. (29) In fact, if the body doesn't receive enough glucose from the diet, it starts breaking down its own fat and protein reserves to produce enough glucose to meet its energy requirements.

Not Stimulating Insulin Secretion

Fructose doesn't stimulate insulin secretion. This is a problem because insulin regulates the amount of body fat by telling the brain to inhibit food intake and increase energy expenditure. While chronically elevated insulin levels (caused by insulin resistance) do induce weight gain and obesity, insulin secretion in response to meals doesn't have the same effect. (32) On the other hand, when you eat glucose, the pancreas produces insulin to signal to the cells to take in the glucose and use it for energy. If there is excess glucose in the blood, insulin signals to the liver cells to take up glucose and store it as glycogen for later when energy requirements are higher. (33)

Insulin Resistance

In addition to fructose not stimulating insulin secretion, it appears that fructose also causes insulin resistance. (34) It's not clear how exactly fructose causes insulin resistance. However, scientists think that the major contributor is high amount of fat in the blood. Since the liver turns excess fructose into fat, there seems to be a direct link between high intake of fructose, high fat levels in the blood, and subsequent insulin resistance.

Leptin Resistance

Leptin resistance is defined as a reduced or absent responsiveness of body cells to the satiety hormone leptin. When leptin crosses the blood-brain barrier, it tells the brain to “turn off hunger” when you are full. If leptin cannot reach the brain, your brain never receives the signal. Studies have shown that dietary fructose ingestion suppresses the transmission of leptin across the blood-brain barrier. (35) Leptin resistance thus causes hunger to persist, leading to obesity. Moreover, leptin secretion is induced by insulin-mediated glucose metabolism. Because fructose, unlike glucose, does not stimulate insulin secretion, meals high in fructose result in lower leptin concentrations than meals containing the same amount of glucose.

Elevating Ghrelin

Ghrelin is a hunger hormone released by the stomach cells. Research has shown that fructose consumption leads to higher ghrelin concentrations, increasing caloric intake and ultimately contributing to weight gain. (36) Glucose, on the other hand, makes you feel fuller after a meal with the exact same number of calories.

6. Spice Things Up

Spicy foods contain capsaicin, an active ingredient found in chili peppers. Along with its slimming effects, capsaicin reduces the risk of tumors (38), has anti-inflammatory and pain-relieving properties, acts as a blood thinner, and is helpful for weight loss. (39)

Spicy foods help to promote weight loss by:

Increasing Thermogenesis (Metabolism)

Capsaicin is a thermogenic substance, which helps your body burn calories by creating heat. Studies suggest that consuming thermogenic food can boost your metabolism by up to 5% and increase fat burning by up to 16%. (40)

Suppressing Appetite & Reducing Cravings

Consuming capsaicin in a form of chili peppers not only suppresses hunger, but also reduces cravings for fatty, salty, and sweet foods. (41, 42) This effect is greater in those who don't consume spicy foods on a regular basis.

7. Hydrate with Water

Water can be really helpful for weight loss. It's 100% calorie-free and keeps you hydrated. The amount of water a person needs depends on many factors, such as body size, physical activity level, medical issues, and environment. As a general rule, drink a minimum of half of your body weight (in ounces) in water throughout the day. For example, if you are 200 pounds, that would be 100 ounces a day. If you struggle drinking plain water, infuse it with fruit, veggies, and herbs.

Water promotes weight loss by:

Burning More Calories

Regular water consumption increases the amount of calories you burn and helps you lose weight. According to several studies, drinking 0.5 liters of water results in an extra 23 calories burnt. (43, 44) If you drink it cold, you will see even better results because your body has to heat up the cold water to your body temperature of 98.6 degrees, which helps burn extra calories and lose weight.

Reducing Appetite

Drinking 2 cups of water half an hour before meal helps reduce appetite and consume fewer calories during that meal. Drinking water not only fills you up without consuming any calories, but it also encourages portion control.

Reducing Calorie Intake

Choosing water over beverages containing sugar, be it natural or added, helps save hundreds of calories each day.

8. Drink Green Tea

Green tea is the most popular drink in the world after water. High green tea consumption comes to no surprise as green tea offers a plethora of health benefits including reduced risk of cancer, heart disease (46), stroke (46, 47), diabetes (48), Alzheimer's and Parkinson's (49), and obesity (48).

Drinking green tea promotes weight loss by:

Suppressing Appetite

Green tea contains compounds called catechins, which have favorable effects on weight loss, particularly around the abdominal area. (50) These catechins elevate a gut hormone cholecystokinin (CCK), which decreases food intake and suppresses appetite. The same catechins also alter energy balance through their interference with the metabolism of carbohydrates and fats. Epigallocatechin gallate (EGCG) is the most active catechin responsible for green tea's metabolic effects.

High Thermic Effect

Green tea also contains caffeine, which stimulates thermogenesis. However, studies have shown that those who consume caffeine with green tea catechins experience a greater decrease in waist circumference - and also lose more weight overall - than those who only consume caffeine. According to Swiss researchers, “green tea has thermogenic properties (...) beyond that explained by its caffeine content” (51) The opposite is true as well – drinking decaffeinated green tea doesn't target belly fat the same way green tea containing caffeine does. It's the synergistic effect of catechins and caffeine that leads to fat loss.

Studies have shown that drinking 4 cups of green tea or taking 2 extract supplements per day for 8 weeks cause a “significantly reduced body weight”. (52) Authors of another study have concluded that drinking 3 or 4 cups of green tea increases metabolic rate by 4% over 24 hours. (51) This translates into 50 – 100 calories burnt per day.