If you’ve struggled with maintaining the weight loss you worked so hard for, scientists say they’ve uncovered a biological explanation: With every kilogram of weight you lose, a new study suggests you get hungrier and your body wants to consume an extra 100 calories.
The research, out of the U.S. National Institutes for Health, is shedding light on why dieters plateau and even go on to regain the weight they’ve lost, the study authors say.
“We’ve known for a long time that people get hungry when they go on diets but we never understood what that translated to into calories per day,” Canadian scientist and study co-author, Dr. Kevin Hall, told Global News.
While there is a library of research on how metabolism stalls weight loss, the NIH scientists wanted to, for the first time, put a caloric number on appetite changes.
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Turns out, for every kilogram of weight loss, people tend to eat 100 calories more than what they were eating before losing the weight. That’s about three times stronger than the slowing of metabolism – in that case, scientists have suggested that for every kilogram of weight loss, energy expenditure slows by up to 30 calories per day.
“This is certainly much bigger than what a lot of people have thought in the past. This is quantifying the increase in appetite associated with weight loss for the first time,” Hall said.
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He’s the scientist behind the study on The Biggest Loser contestants who saw dramatic weight loss that was, ultimately, unsustainable. In that case, he learned that the program wreaked havoc on contestants’ metabolisms, making maintenance nearly impossible.
READ MORE: ‘I feel like a failure’: ‘Biggest Loser’ winner shares her story of gaining back the weight loss
This time around, Hall needed to zero in on food intake, but in a stealthy way. When studies task volunteers with keeping track of calories or appetite, they often underestimate how much they’re eating, leading to inaccurate results.
Instead, Hall relied on data from a study on a new diabetes drug called Invokana. More than 240 Type 2 diabetes patients enrolled in the placebo-controlled, double-blind study – half of the group was assigned to the drug, while the others were given a sugar pill.
People taking Invokana unknowingly burn more calories because the drug aids in increasing glucose output in their urine. Keep in mind, those taking the placebo weren’t burning extra calories at all.
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After a year, those taking the placebo lost two pounds, and those taking the legitimate drug lost seven.
These findings threw scientists off – people taking Invokana were burning about 360 calories per day through their urine. They should have been losing more weight and their weight shouldn’t have plateaued by the eight-month mark.
But Hall figured out what was at play by building an equation that estimated how much people should be eating to lose weight, maintain weight or gain weight.
Those taking Invokana were burning more calories and losing weight, but as they did, their appetites crept up, urging their bodies to eat 100 calories more for every kilogram lost. They weren’t asked to count calories and they didn’t know they were burning more via the drug.
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After this discovery, he looked at data from Weight Watchers participants – he suggests the trend was identical with initial weight loss and a plateau by the half-year mark. Those using the program felt hunger pangs increase as their weight loss progressed.
Hall said his findings offer a silver lining for those battling weight maintenance: “Don’t think of past attempts as some sort of personal failure and that this was a battle of willpower. There’s a huge genetic component here,” he said.
Keep in mind, the study was based on Type 2 diabetes patients who had a lot of weight to lose. Hall said it’s a “first glimpse” but the next steps are to see if this appetite increase applies in the same way to smaller weight losses, and people who aren’t diabetic.
His team’s full findings will be published in the November issue of the journal Obesity. He’s presenting his work on Nov. 2 at the ObesityWeek conference.
carmen.chai@globalnews.ca
Follow @Carmen_Chai
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