People in the wealthier countries are getting fatter. In the USA, about two-thirds of the population are overweight, and about one-fifth are obese.
This obesity epidemic has happened despite an enormous increase in the numbers of weight-loss diets, and the introduction of many low-fat foods.
People will go mental about their specific diet being so much better than any other diet. But the most recent weight-loss research seems to show that diets don’t have to be so complicated.
If your goal is long-term weight loss, the actual diet you follow doesn’t matter. It’s irrelevant whether you reduce just fats, or just proteins or just carbohydrates.
The simple message is that you have to reduce your total calorie intake, and do more exercise.
In one typical two-year-long study, the subjects both reduced their calorie input and did some 90 minutes of extra exercise each week. The goal was to reduce their weight.
Overall, the group’s health risk factors improved. HDL (or “good”) cholesterol increased, while LDL (or “bad”) cholesterol decreased.
Triglycerides, insulin and blood pressure all dropped. The average weight loss was about six kilograms — and this persisted over the long term. Here’s the take home message — the dietary ratios of fats, proteins and carbohydrates were largely irrelevant.
As a result of the study, the advice of the authors was to choose a diet that was balanced, satisfying and did not leave you hungry.
They found that foods with a high glycaemic index tend to spike your blood sugar levels — sending it straight up, and then straight down again, below normal levels. This then stimulates your hunger. If your goal is to lose weight, you should tend to avoid high glycaemic index foods.
The subjects did better with their weight loss goals if they had regular sessions with counselors. So behaviour modification can also help.
A lot of diets tend to focus on the macronutrients of our food — the fats, proteins and carbohydrates.
People (sometimes unscrupulous, sometimes well-intentioned) have made buckets of money by writing books demonising, or promoting, one of these macronutrients.
Some diet books might say eat only protein and fat — but never, ever, ever, eat carbohydrate. Other diet books might claim that proteins were ‘evil’. Sometimes the claim is that a particular combination is the problem. And so on.
By the way, very few of these authors were qualified dietitians. For example, some were accountants, while others were lawyers.
In general, the word ‘dietitian’ is a ‘protected’ word. To call yourself a dietitian, you usually have to do a university degree. But anybody can call themselves a ‘nutritionist’ – even if they have zero training. There’s not a lot of biochemistry, physiology and the other life sciences in your average accountancy or law degree.
But look at the situation of all these different diets from another point of view. Obviously, they can’t all be correct.
It seems that none of them are correct.
In fact, it turns out that while actually losing weight might not be simple, the weight loss plans don’t have to be complicated.
Part of the problem is that we have 200,000 years of evolutionary history, during most of which we did not have a moderately secure food supply from agriculture. So for most of our history, the evolutionary imperative was straightforward — if food is there, eat it right now, because it might not be there tomorrow. But now we live in times of permanent plenty — we are never more than five minutes away from something to eat. And this is part of the increase in fatness.
Fortunately, research (the stuff in the peer-reviewed scientific literature, not the latest diet fad) can help.
Research has found that the differing proportions of fat, protein and carbohydrate in your diet don’t really matter with long-term weight loss.
To lose weight, you have to reduce overall calorie intake in a way that is healthy for your heart. In other words, eat smaller amounts of saturated fats and cholesterol, and greater amounts of dietary fibre. The individual macronutrient choice (fat, protein or carbohydrate) doesn’t matter.
The highly consistent factors in successful weight loss diets were reducing calories and doing a bit more exercise. For example, get a dog and take it for a walk.
So this is the weighty question. How do we make a simple message about eating less and moving more easier to digest …