It makes perfect sense that if we all have different bodies, then we should be on different diets, ones that suit our unique genes and physical needs in order to lose weight, right?
Wrong. Apparently weight loss does not boil down to common sense and dieting is a complicated science.
A new study, earlier this month, has totally dissed the role of genes in weight gain and weight loss. The research, published in the , even shows that there’s no difference between a low fat and low carb diet: you’ll lose the same amount of weight if you restrict your total kilojoule intake, regardless.
American researchers conducted a randomised clinical trial that involved over 600 overweight adults, who followed either a healthy low-fat or low-carbohydrate diet.
Dietary modification remains key to successful weight loss...
All participants were asked to maximise vegetables and minimise added foods with sugars, refined flour products or trans fats.
They were also advised to choose high quality foods that were nutrient-dense and minimally processed, and, where possible, prepared at home.
At the one-year mark, the participants were examined to see if they had lost weight and to determine if their weight loss was linked to their type of diet, genetic makeup or insulin secretion levels.
What the researchers found was that both groups had lost almost the same amount of weight: between five and six kilograms. There were no major differences in body fat percentage or waist circumference between the two groups.
They also concluded that neither factor – genes or insulin secretion levels – had a significantly bigger impact on the participants’ weight loss.
“Dietary modification remains key to successful weight loss,” the study reads. “Yet, no one dietary strategy is consistently superior to others for the general population.”
It's all about how much you eat
Research Associate at The University of Sydney, consultant dietitian and nutritionist, Dr Alan Barclay, says that the study adds gravitas to the belief that when it comes to weight loss, it’s the amount of kilojoules – not the carbohydrate or fat ratio of the diet - that is the most important factor.
“In other words, provided the diet is reduced in kilojoules, and is composed of high-quality foods and beverages, the fat or carbohydrate ratio is not that important – you will still lose weight,” says Dr Barclay.
“We can enjoy a variety of healthy cuisines from Mediterranean style to vegetarian style and still lose weight.”
He adds that, knowing the type of diet you are on makes no difference to your weight loss success, the decision about which kind of diet to follow should be based on your food preferences and cultural background.
We can enjoy a variety of healthy cuisines from Mediterranean style to vegetarian style and still lose weight.
Obesity expert and Professor of Public Health at Griffith University, Dr Lennert Veerman, adds that while most diets work, the real challenge is sticking with them.
“The evidence suggests that after a promising start of the diet, people regain the weight they lost,” says Prof Veerman.
“Instead of ‘going on a diet’, it would be better to find new, healthier habits. But for that to work, most people will need an environment that encourages healthy eating, rather than one that is full of heavily advertised, convenient and affordable junk food.”
But not every expert agrees with the study’s findings. Research director of the Health and Nutrition Program with in the CSIRO Food and Nutrition Flagship, Professor Manny Noakes, says the study makes general claims.
"This study cannot be generalised to all diet and genetic interactions as it only tested three gene variants retrospectively and only looked at weight loss,” says Prof Noakes.
“There are many ways that genes can influence diet and allow better personalisation of diets.
“Salt and caffeine sensitivity, genes that relate to taste preferences, genes that predispose to iron, B12 and folate metabolism and many more.
“I have no doubt that there will be and there is a role for better personalising diets based on genetics.”
She adds that as the evidence is still being collected about the role of genetics in weight loss, we should keep an open mind “before throwing out the baby with the bath water”.
Want to know more about the science behind some of the most extreme dieting methods around? Watch the new season premiere of 'The Diet Testers', airing on SBS from Thursday 1 March at 8.35pm.
