We haven’t become sophisticated enough to predict which people will respond better to certain diets so the message to patients remains simple: cut back the calories and move more.
According to a Stanford University study of adults without diabetes but in the BMI range 28-40, weight loss was similar after 12 months on either a low fat or a low carbohydrate diet.
While there was a wide variation in individual weight change, people in the low fat group lost an average of 5.3kg compared to 6.0kg in the low carb group.
And there was no significant between-group difference in either BMI, body fat percentage or waist circumference.
The study also found no significant effect of three-single nucleotide polymorphisms (SNPs) or baseline insulin secretion on response to the diets.
For example, people with genotypes predicted to be more sensitive to fat such as those with the rs1801282 SNP of the PPARG gene did no better on a low fat versus low carbohydrate diet.
People with high insulin secretion (measured by INS-30) did not benefit more or less on low carb versus low fat diets.
“We conclude that when equal emphasis is give to high dietary quality for both low- fat and low-carbohydrate eating plans, it is not helpful to preferentially direct an individual with high insulin secretion status who is seeking weight loss to follow a lower-carbohydrate eating plan instead on a lower-fat eating plan.”
Commenting on the study, Professor Helen Truby told the limbic that it was certainly worth pursuing biomarkers for response to different diets, but the answer was going to be a lot more complex than single SNPs.
“People up-regulate different genes and down-regulate different genes in response to their environment, their exercise and activity level, and their diet. This study actually doesn’t take that into consideration and you really have to consider environmental impacts.”
Professor Truby, director of dietetics at Monash University, said for the moment, the diet that patients can stick to was going to be their best weight loss solution.
“Reduce calories or increase energy expenditure – either side of the energy equation is going to work but if they need to lose a substantial amount of weight such as 5 to 6kg, they will have to have some kind of management of energy intake.”
“What we’re not good at is being able to predict who is going to be successful and I think we need to learn a lot more about that.”