Facts about diets & weight loss

Eating disorders are complex systems, and they are not as simple as dieting. However, almost every eating disorder begins as a diet. Since diets are ineffective and harmful to health, we fervently wish that no person – and especially no child – ever diet.

The definition of a diet:

A diet is any program that instructs a person to rely on external cues, including what to eat, when to eat, where to eat, how to eat, etc., rather than internal cues of hunger and fullness. Diets include:

– Diet programs including Weight Watchers, Jenny Craig, and Nutrisystem

– “Healthy lifestyles” including Paleo, South Beach, and Atkins

– “Health-based” including like vegetarian, vegan, pescatarian, whole foods only, and sugar-free

– Supplements including meal-replacement shakes meal-replacement bars, slimming teas, Medifast, and Slimfast

– Pharmaceutical drugs to cause weight loss, including Orlistat (Xenical), Lorcaserin (Belviq), Phentermine-topiramate (Qsymia), Naltrexone-bupropion (Contrave), and Liraglutide (Saxenda)

– Pharmaceutical drugs to reduce hunger, including phentermine, benzphetamine, diethylpropion, and phendimetrazine

Key facts:

Most people should not go on restrictive diets – based on the scientific evaluation: does it work? Is it safe? Does it have side effects? The answer for diets is no, not necessarily, yes. [1]

There is significant data demonstrating that diets are faulty products based on faulty assumptions driven by economic incentives. The dieter is accused of failing the diet, but the problem is that the diet fails you. [9]

1. “Successful” diets are not successful 

Diet company CEOs and obesity researchers say diets work because people lose weight, but what you don’t know is that a diet is defined as “working” if it results in 5% weight loss during the early months of dieting. That’s just 10 lbs if you weigh 200 lbs. Have you ever met someone who weighs 200 lbs who would be satisfied, after undergoing the suffering of dieting, with a 10-lb weight loss? [1]

Since the 1940s, hundreds of studies have shown that dieters lose an average of 5-15 lbs over the first 4-6 months of a diet – regardless of the type of diet. [2]

With the 5% threshold, researchers can consider a diet successful, but most consumers of diets do not agree. Few dieters lose enough weight to satisfy themselves.

Diet companies are not required to include information about the effectiveness of a diet in their advertising and promotional materials, and do not provide scientific data proving their efficacy, safety and long-term impact, even though so doing, if the data were compelling, would presumably increase their market share. [1]

Diets have been shown to push the body’s natural set point up, meaning that most people weigh more after dieting than they did before. [12]

2. The science of diet studies

The National Institutes of Health was given $15 million to study diets for 15 years, and research was cancelled two years ahead of schedule. The official reason for cancelling the study was “futility.” They could not find any evidence of benefit for the diet intervention they were studying. It was impossible for the statisticians to find any way to make the data show that dieting could help prevent strokes, heart attacks or deaths from cardiovascular disease, which is what the diet they were studying was designed to prevent. [8]

The Women’s Health Initiative put more than 20,000 women on a diet and followed them for 8 years. After 8 years, there was no change in weight from the starting point, and their average weight circumference, a measure of abdominal fat, had increased. [11]

Very few long-term follow-up studies of diets were conducted before the 1990s, and not many have been published since then. This means we have very little visibility into the scientific facts of what happens after a diet ends, but, as most of us know, what happens most of the time is the weight returns, and the more time passes, the more weight returns. [1]

Out of hundreds of diet studies, only 21 can be considered scientifically valid in that they were a randomized controlled trial in which study participants are divided into two groups in which they have no control over whether they follow the studied diet or not. This is the only way to collect scientifically valid data. In these 21 studies, about 40% of participants actually weighed more at the follow-up than they did before they went on the diet. The final results: dieters weighed an average of 3 lbs less than non-dieters. [1]

The most rigorous diet studies show that about half of dieters will weight more 4-5 years  post-diet than they did before they dieted. [1]

3. The longevity of diet results

The vast majority of diet studies follow participants for only the first 3-6 months of a diet. This is inadequate time to evaluate a diet’s effectiveness, since almost everyone can lose 5% of their body weight in 3-6 months. The real challenge is maintaining the weight loss. [1]

The companies that could provide us with massive quantities of long-term diet success, including Weight Watchers, Jenny Craig, or Nutrisystem, claim they are unable to collect long-term data on the effectiveness of diets. [1]

Richard Samber of Weight Watchers has said that dieting is like gambling. People are driven to return because they believe they may have better luck next time. [1]

The Weight Watchers’ business plan states “Our members have historically demonstrated a consistent pattern of repeat enrollment over a number of years. On average … our members have enrolled in four separate program cycles.” [1]

4. Diets impact brain function

Dieting causes cognitive impairment, including reducing the ability to focus on a task, react to stimuli, plan, make decisions and solve problems. [5]

Dieting reduces memory capacity and distorted time perception. [1]

Diets lead to a preoccupation with food thoughts, often becoming an obsession with food. [4]

Diets reduce cognition while the dieter is dieting. This has been shown based on pre-diet cognition compared to on-diet cognition. [5]

5. Diets are dangerous

There is more and more evidence that diets pose an increased risk for weight gain, weight cycling and disease, eating disorders, and depression. [9]

Dieting is a strong predictor of the development of an eating disorder. Dieters are 8x more likely to develop bulimia or anorexia. [9]

Dieting causes a stress response, releasing the hormone cortisol into the bloodstream. [3]

Dieters are more susceptible to infections, bone density decreases, blood pressure increases, and damaged blood vessels. [6]

Diets cause the body to become more insulin-resistant and fat gets stored in the abdomen as a result. [1]

Dieting can lead to depression, low self-esteem, and anger. [2]

Dieting leads to emotional instability, extreme mood-swings and demonstrated impact of becoming increasingly ineffective at life. Dieters are also seen to have increased obsessive and compulsive behaviors around food and eating, increased shoplifting, and cheating. [7]

Diets slow the rate at which your body burns calories, increases your body’s calorie-efficiency, causes cravings and food obsession, reduces energy levels, lowers body temperature, reduces hunger signals, reduces muscle tissue, increases fat-storage enzymes. [12]

6. Diets don’t improve indications of health

When studies have measured blood pressure, cholesterol, triglyceride, and blood glucose levels, they did not find that participants’ measurements improved with weight loss. [1]

7. The diet industry 

55% of the American population reported dieting to lose weight in 2000, but approximately 95–98% of all dieters who lose weight will regain lost pounds and often end up weighing more than they did pre-diet.The diet industry has a failure rate unthinkable in any other consumer area. [9]

The diet industry has ballooned from $10 billion in 1985 to almost $70 billion in 2012.

8. The worst prescription possible

Doctors frequently prescribe weight loss (dieting) to people who are overweight and obese but imagine you had cancer and your doctor prescribed a medication that had a 2% chance of curing you while causing terrible side-effects. No doctor would do that. And yet the weight-loss prescription persists. [9]

Doctors have the ability to prescribe pharmaceuticals that reduce hunger. These include phentermine, benzphetamine, diethylpropion, and phendimetrazine. These drugs increase chemicals in your brain to make you feel you are not hungry or that you are full. These drugs are approved for just 12 weeks, and are proven to cause: dry mouth, constipation, difficulty sleeping, dizziness, feeling nervous, feeling restless, headache, raised blood pressure, raised pulse. One must wonder how anyone can see any benefit in these drugs. [10]

Doctors have the ability to prescribe pharmaceuticals designed to reduce body fat, reduce the absorption of nutrients by your body, and increase feelings of fullness. These drugs include Orlistat (Xenical), Lorcaserin (Belviq), Phentermine-topiramate (Qsymia), Naltrexone-bupropion (Contrave), and Liraglutide (Saxenda). These drugs disclose that they can cause: diarrhea, gas, leakage of oily stools, stomach pain, constipation, cough, dizziness, dry mouth, feeling tired, headaches, nausea, dizziness, dry mouth, taste changes, tingling of hands and feet, insomnia, headache, vomiting, and abdominal pain. While it may be stated that these side-effects are merely inconvenient (?!), these drugs also lead to decidedly unhealthy complications, including uncontrolled high blood pressure, increased heart rate, liver damage, raised pulse, seizures, birth defects, pancreatitis, thyroid tumors, and suicidal actions. There is no doubt that, given the research available, these drugs do far more harm than good. [10]

Just for fun, check out this parody weight loss commercial:

Facts About Weight & Obesity (1)

Learn the true facts about weight and obesity, and why fear of weight and obesity should not be a concern.


[1] Mann, Secrets from the Eating Lab

[2] Gal and Liu, “Grapes of wrath: the angry effects of self-control”

[3] A. Janet Tomiyama et al. “Low calorie dieting increases cortisol”

[4] Michael W. Green and Peter J. Rogers, “Impaired cognitive functioning during spontaneous dieting”

[5] Green and Rogers. “Impaired cognitive functioning during spontaneous dieting”

[6] Robert Sapolsky, Why zebras don’t get ulcers

[7] Keys et al. The biology of human starvation

[8] National Institute of Diabetes and Digestive and Kidney Diseases

[9] Matz, Frankel, The Diet Survivor’s Handbook

[10] National Institute of Diabetes and Digestive and Kidney Diseases

[11] Howard et al. “Low-fat dietary pattern and weight change over 7 years: the women’s health initiative dietary modification trial”

[12] Bacon, Health at Every Size