RSS feedFollowers of the popular Atkins diet will scream at the top of their voices “No way!”. The incidence of obesity in the world has been rising in the last few decades. According to the National Center for Health Statistics, in 1999-2002 about 16% of American children were overweight. During the same period 28% of men and 34% of women, aged 20-74, were obese. The average weight of men increased from 166 lbs in 1960-1962 to 191 lbs in 1999-2002. There was a similar rise seen among women, rising from 140 lbs to 164 lbs during the same period. The cause of obesity is multifactorial but much interest has been shown in the contribution of dietary macronutrient compositions in causing obesity. Indeed, several popular diet books, “Dr. Atkins’ New Diet Revolution”, “Sugar Busters!”, “The Zone Diet: A Dietary Road Map”, have suggested that increasing obesity may be attributed to the diets recommended for chronic disease prevention by several national health organizations in USA. In particular, these organizations recommend diets that are lower in total and saturated fat and high in carbohydrates from fruits, vegetables and whole grains or fibre-rich foods. So is a diet rich in carbohydrates the root cause of obesity?
A group of 48,835 post-menopausal women, of diverse background and ethnicity, participated in the Women’s Health Initiative (WHI) Dietary Modification Trial (JAMA 2006; 295: 39 - 49) in USA. Forty percent of the women were randomly assigned into an intervention group while the rest were in the control group. Women assigned to the control group received a copy of the Dietary Guidelines for Americans and other diet and health-related educational materials. Women in the intervention group were assigned to groups of 8-15 and had regular meetings with a dietician. The aim of these sessions was to promote dietary and behavioural changes that would result in reducing total dietary fat to 20% of total energy and increasing intake of vegetables and fruits to ≥5 servings and grains to ≥6 servings daily. The women were followed up for a mean period of 7.5 years. Women in the intervention group lost an average of 2.2 kg in the first year and maintained a lower weight than the women in the control group over the 7.5 year period. The weight loss was greatest among women, in either group, who reduced their percentage of energy from fat in their diet. A similar trend in weight loss was also observed in those who increased their vegetables and fruits servings. The women in the intervention group, who had increased the carbohydrate content in their diet, did not show any increase in weight, at any time point, over the 7.5 years.
Three other studies have demonstrated the weight-loss effect of ad libitum (meaning no restriction) low-fat dietary intake. A study involving women previously treated for breast cancer and consuming a high-vegetable, fruit and fibre, low-fat diet showed that these women have small losses in weight (Eur J Nutr 2005; 44: 18 – 25). In the Polyp Prevention Trial (N Engl J Med 2000; 342: 1149 – 1155), both men and women lost weight after having been on a low-fat high fibre diet. In the WHI Feasibility Study, weight loss was observed after 6 months of intervention (Control Clin Trials 1998; 19: 61 – 109).
The American Cancer Society and the Nutrition Committee of the American Heart Association have published guidelines on nutrition. They recommend a dietary pattern balanced in macronutrients, with 20 – 35% of calories coming from fat and 45 – 65% of energy from total carbohydrate as the optimum diet.
The constant societal pressure on some people to stay thin or become even thinner can be oppressive. While it is important to avoid being overweight or obese, going overboard with weight reducing diets is equally not desirable. A diet that cuts out carbohydrate is certainly unhealthy as this would mean cutting out a lot of fruits and vegetables. These foods contain important vitamins and trace nutrients which are crucial to maintaining a normal healthy body. Like all things in life, too much of one thing is not good. Moderation is the key.
