Craig Pickering of DNAFit said that genes besides the three in the Stanford study can contribute to weight loss as well as fat loss and gain, as a small 2007 study found, and that it is "putting the finishing touches" on a study showing that "subjects on a genetically matched diet lost more weight" than did those on a one-size-fits-all low-carb diet.
Gardner and his colleagues designed the study to compare how overweight and obese people would fare on low-carbohydrate and low-fat diets.
Researchers also homed in on genetics to discover if biology would encourage an individual's body to favor a low-carbohydrate diet or a low-fat diet, but they found no associations between gene patterns and a propensity to succeed on either diet. It all depends on the person - although they haven't yet been able to determine the all important characteristics that determine which camp you fall into.
"I think one place we go wrong is telling people to figure out how many calories they eat and then telling them to cut back on 500 calories, which makes them miserable", lead study author and director of nutrition studies at the Stanford Prevention Research Center Christopher D. Gardner said in a press release.
But that wasn't so: on average, participants lost the same amount of weight regardless of which type of diet they went on (somewhere around 5-6kg), and regardless of their particular genetics or insulin sensitivity. About half were men and half were women. All were randomised into one of two dietary groups: low-carbohydrate or low-fat.
Diets are definitely not one-size-fits-all, as what works for one person may not prove successful for someone else.
The individuals began by limiting their daily carbohydrate or fat intake to 20 grams for the first eight weeks. One of the key focuses of the study was to understand how individual factors relate to weight loss and each participant's genome was examined at the start of the study. Similarly, a few women whose DNA did not "match" went through a divorce or other upheaval, ate for emotional comfort, gained weight, and made the mismatched group look awful - a reminder that so many emotional, economic, metabolic, social, and other forces affect someone's chance of losing weight that the effect of genes gets lost in the noise. Lard may be low-carb, but an avocado would be healthier. He said some people are more satiated on whole grains and some people are more satiated with healthy fats.
They then drank pure sugar on an empty stomach to see how their bodies responded to insulin production, needed to convert the sugar to energy.
No significant interaction was observed between diet-genotype pattern or diet-insulin section with 12-month weight loss.
"We really stressed to both groups again and again that we wanted them to eat high-quality foods", Gardner said.
"This study closes the door on some questions - but it opens the door to others". We have gobs of data that we can use in secondary, exploratory studies, ' Dr Gardner said said. Go for whole foods, whether that is a wheatberry salad or grass-fed beef.
'On both sides, we heard from people who had lost the most weight that we had helped them change their relationship to food, and that now they were more thoughtful about how they ate, ' said Gardner.
Meanwhile, Dr. Apovian tells her patients, most of whom have insulin resistance, to eat a diet lower in carbs, particularly grains.
"I'm hoping that we can come up with signatures of sorts", says Gardner.