Talk to anyone who’s successfully lost weight on a ketogenic diet and they’ll tell you — it’s the quickest and easiest way to shed fat. But then, you have people who have had amazing results on kilojoule-controlled, low-fat diets (there’s a reason Jenny Craig and Weight Watchers are so popular.)
So, which is it? What is the holy grail of diets when it comes to fat loss? Well, according to new research published in the journal, JAMA — neither, they’re both equally effective! In a 609 person, year-long study from Stanford University, dieters lost an average of 5 kg — regardless of whether they were on a low-carb or low-fat diet.
“Okay, but different diets work for different people, depending on their genetics,” you might say. Well, according to the study, not exactly. The study found in all cases, the diets worked regardless of whether or not DNA testing indicated it was the best diet for their genetic profile.
In the study, the 609 participants, (aged 18 to 50 with body mass indexes from 28 to 40) 305 participants were randomly assigned to eat a ‘healthy low-fat diet’ for a year, while the remaining 304 were assigned a ‘healthy low-carbohydrate diet. The dieters weren’t strictly monitored or required to stick to a rigid plan. Instead, they were offered 22 hour-long classes led by registered dietitians on how to follow their assigned diet without feeling deprived, as well as general advice on healthy eating.
While the two groups were given different dietary targets (less than 20 grams of carbs for the low-carb group and less than 20 grams of fat for the low-fat group) they were both instructed to maximize vegetable intake minimize intake of added sugars, refined flours, and trans fats; and focus on whole foods that were minimally processed, nutrient dense, and prepared at home whenever possible. Though the researchers didn’t tell dieters to count or cut calories, both groups were eating around 500 to 600 fewer calories each day throughout the study.
At the end of the study, the low-carb group lost an average of about 5.9 kilos per person, while the low-fat dieters lost an average of 5.3 kilos. While there wasn’t much variation in the overall results of the two groups, results varied wildly within the groups. Some dieters lost upwards of 27 kilos, while others gained more than 9 kilos. After the study, the scientists did some DNA testing to determine whether the dieter’s results (or lack thereof) could be explained by their genotype. However, they found that those who had matching genotypes did no better on their diets than those who didn’t.
If that’s the case, what factors did determine whether or not someone lost weight on their designated diets. Well, due to the nature of the study, it was difficult to determine how strictly the participants were sticking to their diets — and how accurately they were tracking. However, it’s safe to say that those who adhered most closely to the targets had the best results.
So, what can we take from all this? Well firstly, you might want to think twice before you shell out for an expensive genetic testing kit. Secondly, while your genes may not affect how well a diet works for you, your lifestyle does — so always pick a way of eating that you enjoy and that you’re actually going to be able to stick to.