Low-fat or low-carb for weight loss?

The eternal question has been whether a low-fat or low-carb diet is more effective in weight loss. Now Stanford researchers have found that neither option is superior. They also established that neither insulin levels nor a specific genotype pattern could predict an individual’s success on either diet.

In the past research has shown that a range of factors, including genetics, insulin levels and the microbiome, might tip the scales when it comes to weight loss. The new study, published in JAMA, homed in on genetics and insulin, seeking to discover if these nuances of biology would encourage an individual’s body to favour a low-carbohydrate diet or a low-fat diet.

More than 600 people participated in the study. At the end of the 12 months, those on a low-fat diet reported a daily average fat intake of 57 grams; those on low-carb ingested about 132 grams of carbohydrates per day.

During the year, researchers tracked the progress of participants, logging information about weight, body composition, baseline insulin levels and how many grams of fat or carbohydrate they consumed daily. By the end of the study, individuals in the two groups had lost, on average, 5.9 kg. There was, however, immense weight loss variability among them; some dropped upward of 27 kg, while others gained close to 9 kg. But, contrary to the study hypotheses, no associations between the genotype pattern or baseline insulin levels and a propensity to succeed on either diet was found.

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