If you want to lose weight, don’t listen to the common advice about dropping the kilos slowly in tiny steps. Do not assume that you can throw a lot of your excess weight by swapping your cheese sandwich with an apple. And do not think that you’ll continue to lose weight at the same rate.
Many beliefs about obesity persist in the absence of supporting scientific evidence, and some even persist despite contradicting evidence.
This is the conclusion of a comprehensive review of the relevant scientific literature, conducted by researchers at the University of Alabama, US, in collaboration with the Danish professor Arne Astrup from Copenhagen University’s Department of Nutrition, Exercise and Sports.
The findings are published in the New England Journal of Medicine.
”It’s not just the media that's spreading this erroneous information around,” says Astrup.
“The myths also exist in the professional ranks and in textbooks. Health authorities and the World Health Organization also play their part in upholding these myths.”
He is, however, quick to point out that nobody is doing this with any harmful intentions. But he does stress that erroneous information has a tendency to be elevated into truths if it’s repeated sufficiently often. And when myths like these are as widespread as they are, they prevent the public and professionals from getting their priorities right in the fight against obesity.
We are usually advised to make small changes in our diet, drink sugar-free soft drinks and take a little walk after dinner if we want to lose weight and maintain a healthy figure.
And this all sounds intuitively correct: by gradually changing your lifestyle, you slowly get used to this new way of living – and it sounds plausible that you then have a greater chance of maintaining a healthy weight in the long run, as opposed to going on a strict diet that makes you drop ten kilos in only a few months.
”But science actually tells us the opposite,” says the professor. “Regardless of whether you pick a sensible diet, exercise, behavioural therapy or a drug, our analysis of the literature shows that it’s those who experience the greatest weight loss in the first 2-4 weeks who have the greatest weight loss the following year. So if you’ve lost a lot of weight after one month, you’re more likely to have lost a lot of weight after a year or two.”
He mentions as an example a randomised clinical trial in which two similar study samples of obese people underwent two fundamentally different diet programmes, of which one led to rapid weight loss, while the other gave a slow reduction in weight.
It turned out that those who lost weight slowly fared no better in the long run than those who lost weight quickly. On the contrary, the participants on the slow diet had a tendency to lose their motivation more quickly than the others because they had to work harder and longer to see the results of their efforts.
In their review of the scientific literature, the researchers only looked at studies that evaluated the effect of diets for adults.
The diets that the researchers focused on are all of high quality, where the obese person receives all the necessary nutrients throughout. In other words, they looked at diets consisting of healthy food, not diet powders.
In this context, rapid weight loss means dropping around one kilo per day. The weight loss should not go far below this level before the participants start feeling frustrated:
”My personal view is that reward is very important to our motivation and perseverance,” says Astrup.
“You get frustrated if after a week of dieting you see that you’ve only dropped 300 grams. This could cause many obese people to give up. Our study also shows that the more weight you lose, the less risk there is that you’ll give up.”