When it comes to weight loss there is a big debate over which is more effective: a low-carbohydrate diet or a low-fat diet. Promotors of each camp will say one is better than the other, and then there is research that suggests over the long term both the low-carb and low-fat diets yield the same body fat loss results.

But when it comes to metabolic health, the size of the fat cells seems to be a much stronger predictor of insulin resistance (an issue that leads to type 2 diabetes) than obesity.

A new study has found a low-carb diet is more effective at reducing the size of fat cells and improving insulin resistance when compared to the low-fat diet. This result is surprising given the weight loss amongst the obese participants was exactly the same.

Fat-cells size shrinks and circulating insulin levels reduce with a low-carb diet

At the most recent World Congress on Insulin Resistance, Diabetes and Cardiovascular Disease, Dr Tracey McLaughlin explained that fat-cell size has a significant impact on our health.

Professor of medicine, endocrinology, gerontology and metabolism at Stanford University, Dr McLaughlin revealed this latest research shows the importance of looking beyond body weight.

“You can lose weight, but if you’re having a lot of carbs and your insulin is sky high, maybe your fat cells aren’t shrinking as much,” said Dr McLaughlin.

Smaller fat cells = improved metabolic health

These results steam from digging deeper into the randomised controlled trial, DIETFITS, which compared low-fat and low-carb diets consisting of the same number of calories to study the weight loss effects.

The two diets focused on whole foods eliminating sugar, refined grains and processed foods.

The results, published in 2018, found that the weight loss figure was the same.

However, when Dr McLaughlin and her team biopsied the fat cells of the study’s 40 overweight participants and tracked their insulin levels, the results of the two diets differed significantly.

After 6 months of dieting:

  • The low-carb participants had a reduction in fat cell size and significantly lower circulating insulin levels, below 50 µU/mL;
  • The low-fat group had no change in fat-cell size and significantly higher circulating insulin levels, peaking above 350 µU/mL.

“It’s pretty clear that when you have a lot of smaller fat cells, your metabolic health is tremendously improved,” said Dr McLaughlin.

A ketogenic diet may be a good choice for type 2 diabetes treatment

“Fat-cell size appears to be an even stronger predictor of insulin resistance than obesity,” said Dr McLaughlin. “[In the study] the more weight you lost, the more insulin action improved, but the more your fat-cell size shrank, the more your insulin action improved.”

While it was noted the study is in its preliminary days, Dr Sarah Hallberg, of Virta Health, also shared research to support the use of a very low-carb diet (ketogenic style) for its health benefits.

Dr Hallberg spoke at the conference about the keto diet and its use to improve blood sugar control, reverse diabetes and reduce cardiovascular risks scores for heart disease.

In particular, Dr Hallberg noted that 91% of participants had reduced or eliminated their insulin use, with 55% in remission from their diabetes in just two years.

“You have a patient who has tried everything, and they are injecting hundreds of units a day of insulin, and you can make a difference like this in the first couple of weeks”, she said.

These study findings suggest weight loss and metabolic health may not just be about eating fewer calories. Following a low-carb diet consisting of whole foods and healthy fats may be what’s required to shrink your fat cells, manage weight gain and improve your overall health.