Eating peanuts as part of a Mediterranean-style diet, containing moderate fat, can help people lose weight, according to a study recently conducted by researchers affiliated with Harvard Medical School and published in the International Journal of Obesity1.

The study, which was equally supported by The Peanut Institute, the International Olive Oil Council and the International Tree Nut Council, also found that people who ate peanuts were able to keep weight off for a longer period of time than people following the traditionally recommended low fat diet

A total of 101 participants of both sex were involved in the study, which aimed to compare the success rate of following a moderate fat diet (35% energy from fat, including monosaturated fat sources, such as peanuts, olive oil and avocados), or a standard low fat diet (20% energy from fat). Both groups consumed the same level of calories and had a low intake of saturated fat. 

The data collected over an 18-month period was analysed by nutrition experts from the Boston-based Brigham & Women's Hospital (BWH) and Harvard School of Public Health. They found that the moderate diet had a greater participation rate and that while both groups lost an average of 5 kg (11lb) during the first year, those following the moderate fat diet were able to keep off a significant amount of their lost weight, whereas the low fat group had regained some of their initial weight loss at 18 months. 

Furthermore, the moderate fat dieters also saw vegetable consumption increase by one serving per day over their baseline diet. Intake of fibre also increased significantly, thus improving nutritional quality overall. 

Lead researcher Kathy McManus, who is also director of the Department of Nutrition at BWH and the director of nutrition and behavioural modification for the Program for Weight Management, commented: "Three times as many people were able to stick to a Mediterranean-style diet versus the low fat diet. Motivation and adherence are very hard to sustain in any weight loss program. 

"Our results demonstrate that people have to enjoy what they eat to stick with it.  Diets that include moderate amounts of fat can be successful because they offer greater variety and taste good."

Jennette Higgs, consultant dietician for the American Peanut Council information office in London, commented on the implications of the Harvard study for British consumers: "This study shows at last that it's not necessary to cut all fat in order to lose weight.  That's good news for anyone trying to lose weight.  A Mediterranean-style, moderate fat, portion- controlled diet allows favourites such as peanuts and peanut butter to be enjoyed guilt-free! 

"What's more, separate studies have now confirmed that monounsaturated fats, such as those provided by peanuts and peanut butter have a positive effect on cholesterol lowering and hence reduce risk of heart disease II.  Peanuts and peanut butter also contribute dietary fibre and other cardio-protective antioxidants, vitamins and minerals."

I K McManus, L Antinoro, F Sacks (2001). A Randomised Controlled Trial of a Moderate Fat, Low- Energy Diet with a Low Fat, Low- Energy Diet for Weight Loss in Overweight Adults. International Journal of Obesity; 25, 5: 1503-1511
II PM Kris-Etherton et al (2001). The Effects of Nuts on Coronary Heart Disease Risk. Nutrition Reviews; 59, 4: 103- 111.
FB Hu, JE Manson, WC Willett (2001). Types of Dietary Fat and Risk of Coronary Heart Disease: A Critical Review. Journal of the American College of Nutrition; 20,1: 5-19