IT’S A KILLER WAY TO BURN MORE KILOJOULES SITTING
It’s the number one question in the health world that seems to tear us apart: Is a low-calorie, low-carb or low-fat diet the key to successful long-term weight loss? Well, a new study published in the journal
BMJ has finally settled the debate once and for all, showing that individuals who follow a low-carbohydrate diet burn 875–1160kJ more a day than those on a high-carbohydrate diet.
To conduct the study, researchers from Harvard University divided overweight and obese people who had previously lost weight randomly into groups.
Each was assigned one of three diets: the first to a high-carb diet (60 per cent of their daily calorie intake from carbs), the second to a moderate-carb diet (40 per cent of their daily calorie intake from carbs), and the third a low-carb diet (20 per cent of their daily calorie intake from carbs).
All the participants’ protein intake remained fixed at 20 per cent, and kilojoules were adjusted to stabilise weight and stop further weight loss, making it more likely that any observed difference in energy consumption was not from weight loss, but from the types of macros (carbs, proteins or fats) consumed.
After the 20-week experiment, the researchers found those on the low-carb diet increased their resting energy expenditure by more than 830kJ a day but the high-carb group decreased their resting energy expenditure.
This translated to 210–290kJ more a day for every 10 per cent decrease in carbohydrate intake.
“If this difference persists – and we saw no drop-off during the 20 weeks of our study – the effect would translate into about a 10kg weight loss after three years, with no change in kilojoule intake,” said principal investigator Cara Ebbeling.
Co-author David Ludwig explained it comes down the insulin levels.
Processed carbohydrates – which “flooded our diets during the low-fat era” – raise insulin levels, he said, which drives fat cells to store excess calories. This increases hunger and slows metabolism, which is “a recipe for weight gain”.
The study found those on the low-carb diet who had high levels of insulin secretion – which is produced after consuming glucose (the sugar found in carbs) – burned even more calories; up to 2000kJ a day.