If you plan to eat less, would you do better to eat less carbohydrate or less fat? A Stanford University study evaluated health and weight-loss benefits of these styles of eating over one year.
The study began with 311 women randomly divided into groups to follow one of four diets that varied in proportions of fat and carbohydrate:
- Atkins: very low carbohydrate, high fat, with no calorie restriction – based on New Diet Revolution by Dr Robert Atkins.
- Traditional: based on the US Food Pyramid, 500 calories per day – developed at Yale University as part of a programme they called LEARN.
- Ornish: high carbohydrate and low fat, with no calorie restriction – based on Eat More, Weigh Less by Dr Dean Ornish.
- Zone: moderately low carbohydrate, with calorie restriction – based on The Zone by Dr Barry Sears.
Around 20% dropped out over the year, so the groups ended up with between 58 and 68 women in each. To begin, these women came into the University study centre for 8 weeks to learn about the diet they were going to follow. Apart from understanding all the recommendations, the women were given no other support or advice. They were given a copy of the book for their diet, and were asked to keep a food diary of what they actually ate for one year.
You may not be surprised to hear that very few of these women actually followed their diets. Even though two of the diets were calorie-restricted and the other two unlimited, all four groups showed a remarkably similar calorie intake over the whole year. They all ate less for the first two months, and then their calorie intake rose in a similar way across all groups for the rest of the year.