Dieting to lose weight? Don’t bother, say experts

Studies show most obese people have a very low chance of losing weight through diet or exercise. Photo / Getty Images
In episode four of Chewing the Facts, Sasha Borissenko explores why diets don’t work, the role of exercise, and the impact of diet culture.
The science is in, diets don’t work — a 2018 meta-analysis of 29 long-term weight loss studies found people regain half the weight within two years. That number increases to 80 per cent within five years.
Another study shows going on a diet, just once, increases the odds of reaching a BMI classified as “overweight”.
And another shows walking 30 minutes a day, five days a week results in no weight loss, namely because exercise accounts for just 30 per cent of energy expenditure at most.
Speaking in the latest episode of Chewing the Facts, neuroscientist Sandra Aamodt says there are two main weapons the brain uses to prevent people from losing a lot of weight, and keeping it off.
“You actually become more fuel-efficient. You become able to do more work with your muscles, using less fuel.
“It is not such great news if you’re trying to cut back on the amount of food you’re eating in the hopes of losing weight, because what that means is that not only do you have to cut back the amount of food that you would logically think it would take to lose a certain amount of weight.
“Then you also have to make additional cuts to compensate for that metabolic suppression that happens as a consequence of getting below your defended range — which is the amount of weight that your brain thinks you should carry.”
People with a BMI of 40 and over have a one-in-eight chance for men, and one-in-seven chance for women of achieving a 5 per cent weight reduction a year.
University of Denver assistant professor and social worker Erin Harrop told Chewing the Facts dieting — together with genetic disposition, personality traits, and trauma — is one of the primary risk factors for someone developing an eating disorder.
Contrary to popular belief, 94 per cent of people with eating disorders are in “normal” and “higher weight” body categories, they said.
“Many eating disorder patients have this belief that they are not sick enough to get help.
“Often we think that a starving body has to be thin, but the reality is that a starving body just needs to be starving and not getting food.”
The US diet industry is also responsible for people developing eating disorders, they said.
“Diet culture is a system of beliefs that we have in kind of modern Western society where we idealise thinness and food restriction, where we define thinness as healthy and healthy as thinness and where we define fat as bad.
“Even our messages about body positivity or body liberation and respectful healthcare for all can still be weaponised by diet culture and by companies that are trying to cash in on that body dissatisfaction.”
Lost and Led Astray director and designer Sarah-Jane Duff rejected diet culture and set up Fat Yoga — an exercise space for all bodies and fitness levels.
“My relationship with my body now is so much better and I cook all the time and I enjoy cooking and I enjoy moving my body.
“There’s nothing safe about a gym because that’s where you start getting all the problems with disordered eating and not liking your body because you start thinking your body has to change.
“Now I move for joyful movement, like I go for walks with friends and I now have a much more active life because I’ve come through the psychological head f*** of not having to lose weight any more.”
Chewing the Facts – new episodes out every Sunday. Produced with the NZ Herald, with support from NZ On Air.
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