Nutrition, Obesity and Weight-Loss Diets

Author: Winston Craig, MPH, PhD, RD.


  • Proponents of the Atkins diet promote the use of pills, along with the diet, for effective weight loss. The recommended supplements include coenzyme Q10 (100 mg/d), carnitine (1500 mg/d), and chromium (1000 mcg/d). There is no reliable science to support the use of any of these supplements to help people burn fat and lose weight.
  • The popular South Beach diet, created by Dr Arthur Agatston, is a slight modification of the Atkins diet. It allows red meat, cheese, and eggs but limits the use of sugar and white flour. Dr Agatston permits carbohydrates and most vegetables high in fiber, but discourages the use of high glycemic index foods such as baked potatoes and carrots. He also discourages the use of butter and fried foods. Any short-term weight loss success would be attributed to a low caloric intake, rather than to any special feature of the diet.
  • Research shows that dieting among adolescents leads to more weight gain than in non-dieters. It is postulated that dieting may induce a cycle of over-eating between the periods of food restriction that more than compensates for the calories lost during the dieting period.
  • Because fruits and vegetables are high in water and fiber, incorporating them in the diet can reduce energy density, promote satiety, and decrease energy intake. Evidence suggests that coupling the advice to increase intake of fruits and vegetables with advice to decrease energy intake is a particularly effective strategy for weight management. This approach may facilitate weight loss because it emphasizes positive messages rather than negative, restrictive messages.
  • In a recent study, age-adjusted mean body mass index (BMI) was significantly highest in meat-eaters and lowest in the vegans. Fish-eaters and lacto-ovo-vegetarians had similar, intermediate mean BMI. High protein and low fiber intakes were the dietary factors most strongly associated with increasing BMI.
  • Increasing the water content of a food can enhance its satiety value, and reduce energy intake. Experiments from Penn State University revealed that when a food of high water content such as soup was consumed there was a subsequent decrease in energy intake at that meal compared with eating a more calorie-dense product such as a casserole. Drinking the equivalent amount of water along with the casserole did not reduce the energy intake of that meal, and the energy intake at the next meal did not increase to compensate for the lower calorie intake of the first meal. Weight management would appear to be better facilitated by focusing on the consumption of foods high in water content.
  • Hydroxycitrate  is a very common ingredient in weight-loss dietary supplements. However, research is lacking to validate the claims made by its proponents that it keeps the body from making fat.
  • Limited experimental data supports the possibility that dietary calcium intake plays a role in regulating a person’s body weight. Calcium appears to bind to fatty acids in the gut and decrease fat absorption.
  • Analysis of data from the Nurses Health Study and the Health Professionals Follow-up Study found a relationship between being overweight and having an increased risk of gallstones, heart disease, stroke, diabetes, and colon cancer.
  • Adding oats to a weight loss diet for a six week period produced an additional 5 point drop in systolic blood pressure and a 21 point drop in blood cholesterol levels compared to the weight loss diet without the oats.
  • The American Heart Association (AHA) issued a recommendation (Oct 2001) against the use of high-protein weight loss programs, saying there are no long-term studies to prove their safety or effectiveness. High-protein diets are usually associated with higher intakes of total fat, saturated fat, and cholesterol, and promote misconceptions about carbohydrates and insulin resistance. People lose weight on these diets because of overall caloric restriction, not because of the types of foods eaten. The AHA says that people who follow high-protein diets are at risk for potential cardiac, renal, bone, and liver abnormalities.
  • Inappropriate, and often unsafe, high-protein diets, such as the Zone diet and the Atkins’ diet, continue to be promoted everywhere. People also continue to be attracted to strange health practices such as colonic cleansing. Chronic overuse of the “cleansing agents” can often produce dehydration, fainting and electrolyte disorders, or eventually they may compromise colonic function. Nevertheless, some people have the notion that they periodically need an internal cleansing to purge the gastrointestinal tract. It is their belief that pollutants and toxins build up in the colon and cause a range of diseases. Laxatives, herbal and fiber capsules and teas are commonly used to “sweep debris from the colon”. In reality, the body has its own self-cleansing system. The cells of the gastrointestinal tract regenerate every 3 days.
  • Data from the Nurses Health Study showed that a higher waist-to-hip ratio (WHR) and a larger waist circumference were associated with a higher risk of coronary heart disease (CHD). Women with a WHR of 0.76 or greater were more than 2 times as likely to develop CHD, while women with a WHR greater than 0.88 were more than 3 times as likely to develop CHD.
  • The risk of gallstone removal is influenced by weight cycling or fluctuations in weight loss. Data from the Nurses= Health Study revealed that risk of gallstone removal was 68 percent for the severe cyclers (20 lbs. or more of weight loss or gain) and 31 percent for moderate cyclers (10-19 lbs. of weight loss or gain). Weight cycling is intentional weight loss followed by unintentional weight gain.


  1. Anika Kesterson July 20, 2016
    • admin September 17, 2016
  2. Deanna Friel July 6, 2017

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