The research, published today in the British Medical Journal, shows that people who choose to eat less fatty foods lose around 1.6kg without dieting. People taking part in the reviewed trials also saw their waist-lines become slimmer, blood pressure drop, and levels of bad cholesterol decrease.
The results prove that weight loss can happen without trying to lose weight – simply by eating a lower fat diet.
The report was commissioned by the World Health Organisation (WHO) Nutrition Guidance Expert Advisory Group (NUGAG) Subgroup on Diet and Health following a request to update their guidelines on total fat intake. The results will be crucial in making global recommendations.
Report co-author, Professor Murray Skeaff of Otago’s Department of Human Nutrition, says that the research provides clear evidence refuting the idea that low-fat diets inherently lead to weight gain.
“The results show convincingly that a lower fat diet helps control body weight and has favourable effects on other risk factors for cardiovascular disease. This is a very important finding.”
The research is particularly important because being overweight or obese increases the risk of many cancers, coronary heart disease and stroke. Reductions in total fat were also associated with small but statistically significant reductions in cholesterols and blood pressure, suggesting a beneficial effect on other major cardiovascular risk factors.
The systematic review included results from 33 randomised controlled trials, in North America, Europe and New Zealand, involving 73,589 men, women and children.
Those taking part had varying states of health. Comparisons were made between those eating less fat than usual (intervention group) and those eating their usual amount of fat (control group). The effect on weight and waist line was measured after at least six months.
The results show that eating less fat reduces body weight by 1.6kg, BMI by 0.56kg/m² and waist circumference by 0.5cm. All these effects were in trials in which weight loss was not the intended outcome, suggesting that they occur in people with normal diets.
The weight loss happened quickly and was maintained over at least seven years.
The researchers say that although “it may be difficult for populations to reduce total fat intake, attempts should be made to do so, to help control weight. They add that high quality trials are needed to examine the effect of reducing fat intake on body weight in developing countries as well as in children.
The research was led by Dr Lee Hooper from the University of East Anglia’s Norwich Medical School.
“Effect of reduction total fat intake on body weight: systematic review and meta-analysis of randomised controlled trials and cohort studies” is published as an open access article in the British Medical Journal (BMJ).
For more information, contact:
Professor Murray Skeaff
Department of Human Nutrition
University of Otago