Stanford University might dismay those who have chosen sides in the low-fat versus low-carbohydrate diet debate.
"Over one year, the low-fat group lost 12 pounds on average", he tells EndocrineWeb, and "group following the low carb diet lost about 13 pounds".
Still, despite these varied results, searchers found no link between one diet and weight loss, over another. That's similar to what other studies have found, but there's an interesting wrinkle. Some dropped upward of 60 pounds, while others gained close to 15 or 20 pounds. Insulin response and DNA don't seem to make a difference.
What does this study tell us?
The study was covered reasonably accurately in the United Kingdom media. For example, a fizzy drink may be low-fat, but it's certainly not healthy.
"Carbohydrates have been deemed "fattening" and "unhealthy" when in actual fact, the science behind carbohydrates is quite complex, and demonising an entire food group is not wise", warns Rhiannon Lambert, leading Harley Street nutritionist and author of Re-Nourish: A Simple Way To Eat Well.
What kind of research was this?
Can't wait to see how copywriters work epigenetics into their taglines.
What did the research involve?
Besides genetic testing, the participants were also given a test to measure whether they were "insulin resistant", that is, whether or not the individual's body responds properly to the hormone insulin, which governs how easily the person absorbs glucose from food. Each group was instructed to maintain the diet for one year. The sessions were run by registered dietitians.
One of the key aspects of the study was ensuring that all of the participants did eat healthily throughout. In all, 241 participants on the low-fat diet and 238 individuals on the low-carb diet finished the study.
After two months they then began gradually increasing their daily carbohydrate or fat intake in small amounts in order to reach a sustainable balance. The academics believe this is because some are more suited to different types of diet as their bodies are better at burning off carbs or fat.
Rather than leave the results to chance, the researchers tested the participants for genetic differences that might influence whether their weight was associated with too many carbohydrates or too much fat. They were put on either a low-carbohydrate or low-fat diet for a year.
Instead of imposing strict food or caloric restrictions, participants were asked to cut down to no more than 20 grams (0.7 ounces) of fat or carbs a day for the first two months.
The only difference between the groups was in lipid levels in the blood.
"In any weight loss diets, adherence to the diet and the overall quality of the diet are probably more important than any other factors", said Hu.
What they did find, though, was that cutting down on sugar and refined flower while upping your intake of vegetables and wholefoods would lead to weight loss.
The theory that some diets work better for some people may still hold true - but not for the reasons previously suggested. Or there may be genetic variations at work - just not the ones that have been identified as potential explanations so far. After, they were allowed to increase their consumption to more manageable amounts for the remainder of the study.
In short, we hypothesized that we would be able to use information from previous studies of the past decade to come up with factors that we could test that would help determine which diet is better for whom.