Men, Women & Dieting

This week’s note comes from a global collaboration between researchers in Europe, Australia and New Zealand. The research was reported as “men are more successful than women at dieting” (Ref 1) and this was one of the study findings. However, it was by no means the only finding and the reasons for observed differences are interesting.

Let’s look at the study, what it found and the explanations that the paper offered for men being more successful than women at dieting. I’ll then share my own top 5 observations, gathered over many years, for why men tend to do better at weight loss than women…

The study

There is an ongoing study called The PREVIEW lifestyle intervention study, which is (to date) the largest, multinational study concerning prevention of Type 2 diabetes (Ref 2). The project started in January 2013 and is scheduled to last for six years. The primary goal of PREVIEW is to identify the most efficient lifestyle pattern for the prevention of type-2 diabetes in a population of pre-diabetic, overweight or obese, individuals.

The goal of this particular study was to assess whether or not very low calorie diets would achieve different outcomes in men and women. Insulin resistance was the primary outcome of interest to the researchers. The secondary outcomes of interest were: weight loss; fasting blood glucose; fat mass; fat-free mass (lean body tissue in essence); cholesterol; bone mineral content and bone mineral density among others. The researchers tested many different things to give themselves the best possible chance of finding some significant results (the more you test, the more chance you have of finding something).

For this particular paper, 2,224 individuals (1,504 women and 720 men) were selected for study. The participants were aged between 25-70 years and they were already enrolled in the PREVIEW study. They had a BMI of 25 or above (the average BMI was 35) and they met the American Diabetes Association criteria for pre-diabetes (Ref 3). Most were Caucasian (88%); the remainder were Polynesian (4%), Asian (3%), Hispanic (2%), Black (2%) and ‘other’ (1%). The study admirably reported that the lack of ethnic diversity meant that the results were not generalisable to all ethnic groups.

The intervention was for all participants to undertake a very low calorie liquid diet for eight weeks. The diet was provided by Cambridge Weight plan and the lead author declared conflicts with “The Cambridge Weight Plan, UK.” This doesn’t make the results any less interesting.

The diet comprised four Cambridge diet sachets a day – three dissolved in very low fat milk and the fourth in water. The sachet and milk intake was calculated as providing 810 calories a day, 85g of protein, 5g of essential fatty acids and the daily requirements for vitamins and minerals. The macro nutrient composition of the sachets and milk together was 44% protein, 41% carbohydrate and 15% fat. (That works out at approximately 80g of carbohydrate per day). The article reported that the fibre content was relatively low at 13 g/day. Participants were therefore allowed to consume 375g of low-starch vegetables “such as tomatoes, cucumber and lettuce” per day (this would add approximately 15g of carbohydrate to the daily intake).

Participants attended group visits at the intervention sites at weeks 2, 4, 6 and 8. This high level of engagement was reflected in a high completion rate – 2,020 (91%) of people completed the 8 week programme.

The results

 

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