This time of year will generally see an upsurge in the number of people looking to lose some weight, often on account of the extra body baggage they’ve accumulated over the festive season. Many people will be tempted to take the oft-touted approach of ‘eating less and exercising more’. Here’s what we know from the science about these approaches:
1. Calorie-controlled diets rarely lead to significant, sustained weight loss
2. Adding aerobic exercise to a ‘diet’ generally does precious little to improve the results
These facts (and they are facts) appear to defy logic and common sense. But as I describe in my new book Escape the Diet Trap published today, there are several well-understood mechanisms through which ‘eating less and exercising more’ destines the majority of us to weight loss failure.
One thing calorie-controlled diets have been shown to do is stifle the metabolism. But the extent of this can be profound. In a seminal study I describe in my book known as the ‘Minnesota Experiment’ (conducted shortly after the 2nd World War), a 1,600 calorie-a-day diet led to weight loss of 20-26 per cent in a group of men over a 24-week period, but their total energy expenditure fell by almost 40 per cent.
Many men also became so hungry they obsessed about food and had little interest in anything else. Some of them experience debilitating physical and mental symptoms. This, by the way, was on a diet containing more calories than many weight loss diets advocate. The diet was also rich in carbohydrate and low in fat – precisely the sort of diet health professionals and our governments usually advocate for weight loss.
When the men were allowed to eat in an unrestricted manner again, they generally consumed huge quantities of food and. By the time their eating naturally returned to normal levels, their fat levels were, on average, 75 per cent higher than when they started.
The Minnesota experiment is just one study, but its findings I think reflect the experiences of countless individuals who:
- have eaten less (gone on a diet) and lost weight
- have got hungry and ‘toughed this out’
- have had their weight loss plateau
- have defaulted and found themselves eating almost uncontrollably
- have regained weight quite rapidly
- have ended up heavier than they were before
It is the crashing failure of calorie-based approaches to weight loss than cause my sometimes to rail against articles such as this one. In short, it raises our awareness of the fact that many people are unaware of the calorific nature of foods including hummus (a blend of chick peas/garbanzo beans, sesame seed paste, olive oil and lemon juice).
Hummus might indeed be calorific, but one could argue that the quality of those calories are decent enough. All the constituents of this food are essentially whole and minimally processed. It contains a reasonable blend of protein, fat and carbohydrate. It’s a food that is likely to sustain us quite well. Could we say that for a not-so-calorific food like spinach or broccoli? I do have some reservations about hummus, but this has nothing to do with its calorific nature, and is actually related to the fact that beans (and other legumes) are relatively rich in substances called lectins that can be toxic to the body.
The point is this: judging a food by its calorific content is misguided at best. Not only does ‘calorie control’ rarely lead us to lasting weight loss, it can cause us to eschew nutritious, healthy foods in favour of nutrient-depleted junk (including many processed foods marketed to slimmers).