Should we tailor our weight loss efforts to our genes? Image adapted from: Robert Owen-Wahl; CC0

There's no point demonising either carbs or fats

Gene-based diets are not the solution for weight loss

Diet advice is everywhere these days, and sifting through what’s legitimate and what’s just a bunch of marketing hype can be tricky. Should we switch to paleo? Cut out red meat? Avoid all fats, or just saturated fats, or just trans fats? Quit sugar? And what about carbs!?

More recently, the trend has been for eating according to your genetics. Some dieticians and nutrition experts began to recommend a more individualised approach to healthy eating, with food intake tailored to your own unique genetic makeup.

Slices of bread with some butter — Are fats or carbs the bigger enemy? This study suggests that either a low-carb or a low-fat diet will help you lose weight, regardless of your genes. Image adapted from: congerdesign; CC0

However, new research from Stanford University casts doubt on this approach. Researchers spent 12 months tracking the diets of over 600 overweight adults to determine whether a healthy low-fat diet or low-carbohydrate diet helped with weight loss.

The researchers also studied whether matching these diets to each participant’s genotype pattern or insulin levels had any effect on which type of diet was best for them. Previous studies have suggested that your genes or how your body processes sugars might change the effectiveness of your diet.

It turns out we might not need to worry about our genes if we want to fit into our jeans. The researchers found that participants in both the low-fat and low-carb diet groups lost roughly the same amount of weight. More importantly, there was no link between genotype or insulin production in determining whether one diet was more effective than another.

But is this just one more contradictory study in a sea of ever-changing dietary advice?

There are a few things that make this study particularly credible. The study had a fairly large sample size (number of participants), resulted in significant weight loss, and most of the participants stuck to their diets for the full 12 months. These factors all make the statistical results more trustworthy, and therefore it’s more likely that scientists could detect any links between genes and diet effectiveness.

It’s worth noting that all of the participants in the study consumed fewer kilojoules overall, and changed the types of foods they were consuming, compared to their previous diets. It’s not as simple as ‘cutting out carbs’ or only eating low-fat foods; what matters is the total energy intake and whether foods are nutrient-dense or full of junk.

Hands reaching towards some small bowls of berries and cereal on a dark surface — It’s always better to choose foods high in nutrients instead of foods full of junk. Image adapted from: Lukas Bieri; CC0

This study adds further support to the idea that there’s no point demonising either carbs or fats: we need both for our bodies to function, just not too much! What’s even more important is the amount of carbs and/or fats we consume relative to protein, as this ratio is what determines our total energy intake.

So, while we know that some diets work better than others for some people, we’re still no closer to figuring out exactly why. Until then, there’s probably no specific strategy that could be called ‘the best’ for everyone, other than simply eating a balanced diet rich in high-quality nutrients and fewer kilojoules overall.