New scientific research has shown that low-carbohydrate high-fat diets, made popular by the likes of the Atkins diet, do not achieve more weight loss than low-fat high-carbohydrate diets. Worryingly, the research, lead by Dr Steven Hunter from the Royal Victoria Hospital, Belfast, also shows significantly increased risks of cardiovascular disease for people following low-carbohydrate high-fat diets.
The research shows that the risks of low-carbohydrate high-fat diets far outweigh the potential benefits gained by overweight and obese people through weight loss, including improvements in blood pressure and risk factors for coronary heart disease.
The research results, released hot on the heels of both National Obesity Week and World Diabetes Day, are particularly important for nearly a quarter (24%¹) of the UK adult population, and 16% of the child population, now classified as obese and at risk of Type 2 Diabetes – 80%² of all people diagnosed with Type 2 diabetes are overweight.
Type 2 Diabetes is the result of inadequate insulin production and/or insulin resistance, which means that the right levels of glucose (our main source of energy from food) are not maintained naturally by the body. There are 180 million people in the world with diabetes and the World Health Organisation predicts this number will double in the next 20 years.
Dr Hunter, Royal Victoria Hospital, Belfast, said: “The worldwide obesity pandemic is a major public health concern and strongly linked to rises in diabetes and cardiovascular disease. By advocating low-carbohydrate high-fat diets as a weapon against obesity and diabetes, health professionals could be contributing to a dangerous rise in cardiovascular disease”.
The research study, conducted among a group of obese pre-diabetic adults, compared the results of following a low-fat high-carbohydrate diet (20% fat, 60% carbohydrate) with a high-fat low-carbohydrate diet (60% fat, 20% carbohydrate). It showed that in all areas, other than the risk of cardiovascular disease, the diets have equal health benefits. The same amount of weight is lost; there is no significant difference in the body’s glucose uptake or production; and meal tolerance-related insulin secretion is comparable. However, the study revealed a significant difference in overall systemic arterial stiffness and pointed to increased cardiovascular risk factors from high-fat low-carbohydrate diets.
Dr Hunter continued: “High-fat diets have become popular because they seemingly promote more rapid weight loss and because of their palatability. However, we now have proof that they do not help people lose weight any faster than more conventional diets, and the potential negatives of increased cardiovascular risks far outweigh the potential positives of more easily sustained dieting/weight loss, especially when there is a proven and safe alternative in low-fat high-carbohydrate weight loss diets.”
According to Dr Hunter, the challenge now is to find ways to make low-fat high-carbohydrate diets more palatable and easier to maintain, so that a long-term positive outcome is achieved.
The Food Standards Agency says that saturated fat should account for less than 11% of the total diet for a normal person, and Dr. Hunter concludes: “If your New Year’s resolution is to lose weight, make sure you do it the right way and don’t burden your body with additional unnecessary health risks by falling for the lure of the seemingly easy and fast weight loss offered by high-fat diets. The best approach for your overall health is a low-fat high-carbohydrate diet, coupled with exercise.”
¹ NHS Statistics on obesity, physical activity and diet: England, January 2008, published 31 January 2008
² Diabetes UK
Bradley U et al. Low-fat versus low-carbohydrate weight reduction diets: effects on weight loss, insulin resistance and cardiovascular risk. A randomised trial. Diabetes. December 2009, vol.58, no. 12, 2741-2748
Low-Fat versus Low-Carbohydrate Weight Reductions Diets: Effects on Weight Loss, Insulin Resistance and Cardiovascular Risk A Randomised Control Trial, is one of the first studies to determine augmentation index, by measuring arterial stiffness using pulse wave analysis, in relation to cardiovascular risk.
Research Design and Methods: the research investigated a low-fat (20% fat, 60% carbohydrate) versus a low-carbohydrate (60% fat, 20% carbohydrate) weight reduction diet in 24 overweight/obese subjects, BMI 33.6±3.7 kg/m², age 39±10 years (mean ± SD), in an 8 week randomised controlled trial. All food was weighed and distributed and intake calculated to produce a 500kcal/day energy deficit. Insulin action was assessed by the euglycaemic clamp and insulin secretion by meal tolerance test. Body composition, adipokine levels and vascular compliance by pulse-wave analysis were also measured.
The Low-Fat versus Low-Carbohydrate Weight Reductions Diets: Effects on Weight Loss, Insulin Resistance and Cardiovascular Risk A Randomised Control Trial study, by Dr Steven J Hunter, was supported by RRG 5.42 (PI SJH) from the Northern Ireland Department of Health and Social Services Research and Development Office and by an unrestricted research grant from The Sugar Bureau (UK).
Diabetes is a common health problem which affects around 3-4% of the UK population.
The majority of people with type 2 diabetes are overweight. Therefore, weight management is a crucial aspect in the prevention of type 2 diabetes and the management of diabetes in general.
The diet for people with diabetes is no longer a special one, but merely follows the basic principles of healthy eating, ie a low-fat, high-carbohydrate diet.
One of the prominent changes of the recent nutrition guidelines from Europe is the relaxation on dietary restriction of sugar and high-sugar content foods, providing blood glucose levels are kept in control. This is because sucrose (table sugar) does not increase blood glucose to a greater extent than similar amounts of starchy foods like bread, potatoes or rice.
FAQ on sugar and health
Diabetes and Nutrition Study Group of the EASD. 2000. Recommendations for the nutritional management of patients with diabetes mellitus. European Journal of Clinical Nutrition, 54, pp353-355.
American Diabetes Association. 2008:
Nutrition recommendations and interventions for diabetes: a position statement of the ADA. Diabetes Care, 31suppl, pp61-78.
Black RN et al 2006.
Diabetes; 55: 3566-3572.