Whether it’s to fit into clothes from a couple of years ago, or to be a little healthier, we tell ourselves we need to – and often try to – lose weight. And our family, friends and medical caregivers tell us we should and can, if only we put in a little effort to diet and exercise.

But new research is upending everything we thought we knew about dieting and weight loss. The truth is, no matter what we do, our weight has a “set point” that’s almost impossible to beat.

Diets are efficient at short-term weight loss. All things being equal, it takes roughly 77 hours of exercise to lose 1 pound; at one hour of exercise a day, that’s 77 days. Conversely, it only takes cutting 500 calories a day from an otherwise balanced diet to lose the same amount in a week. In theory, by diet alone you could drop 11 times the amount of weight you would through exercise alone, in the same amount of time.

But efficient is not the same as effective. Dieting messes up your metabolism to the point that not only do 80 to 97% of dieters regain the weight they lost, depending on which study you cite, but 41% of them regain even more. In fact, in the long term, dieters are more likely than non-dieters to become obese.

Until recently, this regain has been blamed on the person – they slacked off, weren’t disciplined enough with their diet or exercise. But a new study that followed contestants on the American reality TV series The Biggest Loser (on which obese people compete to lose the most weight) has revealed that our brains are hard-wired to regain weight that is lost.

Six years after competing on TV, most contestants had regained some – if not all or more – of the weight they shed, despite maintaining active lifestyles and low-calorie diets. This seems to confirm the idea of a “set point,” a theory of weight that suggests the brain recognises a range of weight as the body’s norm and fights to keep it there.

Set point theory has been around for more than 30 years, but until The Biggest Loser study, it wasn’t clear just how far the brain will go to recover set point weight. Now we know: pretty far.

While prior to losing weight, contestants had a resting metabolic rate that matched their size, after losing and regaining weight, their resting metabolic rate never recovered; they had the metabolism of a much smaller person even after they gained back the pounds.

A quick refresher: Metabolism is the process through which your body converts food to the energy you use for everything from breathing to pumping blood. Your rate of resting metabolism – that is, the rate at which calories are ‘burned’ to produce energy when you’re not doing physical activity – is dependent on your size, muscle mass, sex and age. Bigger people, or people with more muscle, have a higher metabolic rate than smaller people, or people with less muscle; men have higher metabolic rates than women; and everyone’s metabolism slows with age.

At the same time, everyone’s resting metabolic rate is right for their size/sex/age/muscle mass (barring a few, rare conditions). That is, until you diet.

When your intake of calories drops – as it does during a diet, whether through skipped meals or lower-calorie food – your resting metabolism drops, too, in an effort to conserve energy and prevent starvation. So while you’re consuming fewer calories, your body also adjusts to get by with less energy.

This is why most weight loss plans call for exercise, too. Exercises that build muscle raise resting metabolism, while the physical activity itself burns calories at a high rate. The idea is, the body will have to supplement the few calories with its fat stores to provide the necessary amount of energy, leading to weight loss – and off-setting the metabolic suppression dieting causes.

And it does – for a time. A rigorous combination of diet and exercise is how the contestants lost weight to begin with. But because of the way the brain suppresses our metabolic rate in response to weight loss, the weight will almost always come back.

It would be easier to write off these findings as a case study on the dangers and consequences of obesity. Except, a 2006 study of professional male athletes found men who regularly dieted and regained weight to meet competition weight standards (as in boxing and wrestling) were three times more likely to become obese by middle age than their counterparts in sports that had no such requirements.

It upends all of the traditional thinking around weight loss – the fastest growing segment of the roughly 1 trillion-rupee Indian wellness industry. Which begs the question: Just what are we paying for?

Weight loss experts now seem to be focusing on how to ‘reset’ set point weight, but at best, this seems like an educated guess; research to prove it’s possible and via what method is lacking.

Still others are making the case that we shouldn’t even try. While obesity undoubtedly correlates with health problems like diabetes and heart disease, there is no clear evidence that it is the cause, which means weight loss might not be the preventative investment in health it is often promulgated as. As one expert says in the Slate article linked above:

“We make all these recommendations, with all this apparent scientific precision, but when it comes down to it we don’t know, say, how much fat someone should have in their diet,” says Asheley Skinner, a pediatrician at the University of North Carolina–Chapel Hill School of Medicine. “We argue like we know what we’re talking about, but we don’t.”

Instead, there’s evidence to suggest carrying a little (though not excessive) extra weight might be a good thing; studies have found individuals who fall under the clinical categories of “overweight” have less risk of early mortality compared to their thinner, “healthy-weight” counterparts.

In short, nothing is clear when it comes to diet and weight loss, and it’s best to be skeptical when a person or product tells you otherwise. As for those 10 to 20 pounds – we might just have to learn to be okay with them.