Why does your weight get stuck at a point?
If you can’t seem to keep kilos off, no matter how hard you try, give yourself a break – you could be predisposed to a weight ‘set point’.
In theory, losing weight should be as simple as burning more kilojoules than you eat. And it often is – to start with.
But research shows most people who lose weight by dieting put it back on and one explanation is the “set point theory”.
What is your weight set point?
Your set point is the weight your body is programmed to be.
“A set point is the weight at which the body defends weight to,” says Austin Health Weight Control Clinic head and endocrinologist Professor Joseph Proietto, who specialises in diabetes and obesity.
University of Sydney Charles Perkins Centre obesity researcher Dr Nick Fuller says: “As humans we have an evolutionary propensity to get back to the weight we were before the diet, which is our ‘set point’.”
How your set point affects weight loss and gain
When we try to lose weight from what our genes determine it should be, hormones that influence hunger react in a way that increases appetite.
“When someone loses weight, the levels of these hormones change in a direction to increase hunger and we have shown these changes are long lasting,” Prof Proietto says.
A 2017 study found a common side effect of weight loss is a slower rate of energy expenditure and lower levels of hormones that suppress appetite.
“In other words, the body makes you hungrier after you lose weight, meaning that it never gives up trying to take you back to your set point,” Prof Proietto says.
This programming can be traced back to our primitive ancestors.
“The genes that cause weight gain were selected over evolution because when we were still hunter-gatherers, the ability to store fat effectively offered a survival advantage,” says Prof Proietto.
“But now with too much food, there is a mismatch between what these genes are meant to do and the new energy-rich environment.”
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What determines your weight set point?
Our set point is determined by genes, but it can be impacted through life by environmental influences such as stress, pregnancy, high energy food, and chemicals.
“People are born with their tendency to be either slim or more likely overweight, or to have genes that are susceptible to epigenetic triggers,” Prof Proietto says.
The environmental influences your genes were exposed to prior to conception can impact your set point.
A German study found the offspring of mice fed a high-fat diet were more susceptible to obesity and diabetes – even when the babies were conceived by IVF and carried by and born to healthy mothers.
“The first 1000 days, which is the period from conception to the end of a child’s second year, are important,” says Dr Fuller.
The body’s tendency to regulate weight by triggering mechanisms that will return it to its set point after weight loss doesn’t work well in reverse.
That means if you gain weight, your body isn’t predisposed to help you shed it.
“And then this higher weight becomes your new set point,” says Dr Fuller.
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Can you lower your weight set point?
This is where the experts differ.
Dr Fuller believes gradual weight loss may enable the body to reset its set point.
“Gradual weight loss of 2kg one month, followed by a month-long weight-loss break, effectively resets or lowers the body’s set point,” says Dr Fuller.
“This allows you to lose 12kg – and keep it off – in one year, when people usually lose that amount in just a few weeks on a diet and then put it all back on.”
In contrast, Prof Proietto argues your set point cannot be changed, but it is possible to shed kilos below it.
He says a very low-calorie diet or a ketogenic diet can assist people in losing weight below their set point – but the real struggle is in keeping it off.
While he says a few people are able to resist the body’s increased hunger cues following weight loss, most require assistance to achieve long-term success.
“Once you’ve gone through a ketogenic diet, got yourself back to a healthy weight, you actually need medications to maintain weight,” he says.
“In the maintenance phase, we have a number of hormone medications that makes us feel full after a meal.”
Prof Proietto recommends working with a qualified health professional to help you safely manage weight loss and explore suitable weight maintenance options.
Written by Karen Fittall and Claire Burke.
