Don't scold yourself for gaining weight, your body is wired to return to a natural set point - but there may be ways to shift it

• Weight regain happens because our bodies want to return to their set point weight, according to an obesity doctor.
• Evidence suggests that each person's set point is a range, and some people's set point weight will naturally be higher than others.
• If you mix months of slow weight loss with months of maintenance, that may help to keep weight off, Dr Nick Fuller said.

Regaining weight is not dependent on willpower, but biology, according to a top Australian obesity doctor and researcher.

Dr. Nick Fuller told Insider that the extreme way most people diet makes bodies more inclined to return to their starting weight afterwards.

"Dieting and weight loss is seen as a huge stress on the body, and the body works to eliminate that stress by shutting down and resultingly, ensuring you climb back to your starting weight," he said.

When we try to lose weight, our bodies resist and a number of physiological changes occur, Fuller said. For example, our thyroid shuts down, metabolism slows, and our appetite hormones tell us to eat more.

This biological response stems from our hunter-gatherer ancestors - whose bodies adapted to periods of deprivation when food was scarce and held on to fat, which is known as metabolic adaptation.

Research suggests everyone has a natural set point weight

A person's starting weight can be thought of as their set point weight, which is the weight you remember being for a long period of time in your adult life, according to Fuller, who is based at the University of Sydney.

Evidence suggests that each person's set point is a range, and some people's set point weight will naturally be higher than others.

According to Carol Harrison, Senior Exercise Physiologist at The University of Texas MD Anderson Cancer Center, the body will defend itself to stay within a few pounds.

"The set point is established over a long period of time. It's a very complex thing, but it appears that it is your body's attempt to regulate itself, and that attempt results in a certain weight," Harrison said.

It may be possible to change your set point weight, Fuller said

If you're trying to lose weight but feel hopeless about your set point, you don't have to give up - you can change it with slow dieting, Fuller said.

His weight loss philosophy, Interval Weight Loss, entails alternating between a month of weight loss (aiming to lose 2kg or 4.4lbs) and a month of maintenance, meaning a person would lose 12kg or 26.5lbs over a year.

The weight loss months involve eating five times a day, one "treat food" (such as cake) and one meal out each week, 30 minutes of exercise (of varying intensities) six days a week, sleeping 6-8 hours a night, and three TV-free days a week (with no more than two hours of TV on the other four days).

The maintenance months are largely similar except with two meals out and two "treat foods" each week, one fewer workout (which can be lower intensity), and one more day of TV.

Losing weight in four-week cycles means your body doesn't fight itself and regain doesn't occur, Fuller said.

"The weight maintenance months allow your body the rest it needs and prevents the physiological responses that come with diets and weight loss programs," he said.

Once you get to your goal weight, you stick to the maintenance guidelines forever.

Are there other ways to change your set point?

Fuller maintains that no conventional diet regime addresses a person's set point which is why people regain afterwards, but this may not be wholly true.

According to MD Anderson Senior Exercise Physiologist Carol Harrison, there are two key factors to bear in mind when dieting if you want to change your set point: losing weight slowly so your body can adjust, as Fuller recommends, but also getting support from a dietitian or therapist along your journey so you can be aware of your cravings and how your body is reacting.

Simply eating less and moving more, without taking your time and also working on your mindset, will not lead to lasting weight loss, Harrison said.

But more drastic weight loss methods may lower weight set point.

Although only limited research exists, there is evidence (such as this 2016 study on rodents by Louisiana State University) to suggest that weight loss surgery, such as a gastric bypass, can change a person's weight set point.

According to board-certified, fellowship-trained bariatric surgeon Dr. David Oliak, weight loss surgery doesn't lead to the same natural resistance that comes with dieting, such as increased hunger and decreased metabolism.

And Fuller agrees: "Bariatric surgery can alter the appetite wiring system and prevent the increase in appetite that comes with dieting because the anatomy of the gut is altered, which, for example, then reduces the amount of ghrelin produced by the stomach (ghrelin tells us to eat more)."

Dr. Spencer Nadolsky, an obesity specialist, said the notion that bariatric surgery lowers or resets a person's set point is still a hypothesis.

"One may not see the metabolic adaptations seen in just diet and exercise as you see with surgery," he told Insider.

"However, the biggest physiological driver to weight regain is appetite, which bariatric surgery deals with. Whether it actually resets one's set point or not, it's a very powerful tool that combats that appetite driver."

'Dieting has accelerated the obesity epidemic,' according to Fuller

Fuller's Interval Weight Loss plan is a long game approach, and he believes weight loss should not be considered successful until a person has kept it off for five years.

The trouble is that people want big results fast.

"We have been doing the same thing for decades and all it has done is contribute to the very problem it proclaims to solve - dieting has accelerated the obesity epidemic," Fuller said. "If dieting worked we wouldn't see people signing up to the same diets and same weight loss programs repeatedly every year."

Fuller believes the issue with conventional dieting is that it doesn't address set point, and he said many diets are unsustainable and can also cause both mental and physical damage.

"People need to be educated on why they are failing on their weight loss attempts from people who know what they are talking about and what they can do to restore control of their health and weight," Fuller said.