Shedding those extra kilos, they say is less about what you eat and more about who you are at a biological level. [Photo: Bigstock]

When it comes to dieting, one size doesn’t fit all

31 July, 2017

High carb, high protein, high fat – every kind of diet seems to work for someone. But nobody knows why – until maybe now.

Excess weight is a major risk factor for diabetes and other health conditions, including heart disease and cancer. And each year, millions of us go on diets in an attempt to lose some of that excess weight, often with disappointing results.

According to researchers at the University of Copenhagen the problem may lie in our belief that when it comes to dieting one size fits all.

In a new study in the American Journal of Clinical Nutrition they argue that the long-raging debate over whether cutting carbs or cutting fat is a better way lose weight is a false dichotomy.

Shedding those extra kilos, they say is less about what you eat and more about who you are at a biological level.

Just eating less isn’t working

What you need to know

» Weight loss programmes can have highly variable results with some people losing weight well and consistently and others finding it hard to shift excess weight.

» If a calories in and calories out approach to dieting is the most rational way to lose weight everyone should succeed using this method. But they don’t

» New research from Denmark suggests that different individuals, classified by the levels of glycaemic control, need different weight loss approaches.

» In their study prediabeteics lost more with a low glycaemic load diet, while those who had type-2 diabetes did better with a high-fat and low-carbohydrate diet- results which they say suggest a more personalised approach to weight loss is needed.

In the last three decades, the fight against obesity has focused on what seems like reasonable advice: eat less and exercise more. But as time and climbing obesity rates show, this strategy isn’t working. In fact there are studies to suggest that we are, on the whole eating fewer calories, but weight continues to rise.

“When the obesity problem would not go away, it led to the fat reduction era with the replacement of a lot of fat with fibre, but also a lot of starch and carbohydrates, and in some instances more sugars, which did not solve the problem. In fact, the obesity rate when up,” comments lead researcher Arne Astrup, professor and head of the University of Copenhagen’s Department of Nutrition, Exercise and Sports. “This started a new trend, the Atkins Diet, and the major focus on restricting sugars and starchy foods, which like the low-fat diet worked for some, but not everyone.”

Head-to-head comparisons of the two diets showed them working equally well for some, and not well for others, which, according to Astrup, “didn’t make sense”.

In an attempt to understand these apparent contradictions, Astrup and fellow researchers began with the assumption that no diet fits all needs and started searching for biomarkers that might predict weight loss success based on different diets and body types.

Tailored results

They looked at weight loss and gain in more than 1,200 adults, who participated in three randomised clinical trials conducted in eight European countries. Specifically they were investigating at the impact on weight of eating a diet higher in protein, higher in fat, lower in carbohydrates and on the glycaemic index, higher in carbohydrates and the glycaemic index, higher in fibre and whole grains or lower in fibre in whole grains.

Instead of simply looking randomly at people, they zoomed in and looked at impact of the diets on people who prediabetic, diabetic or had normal glycaemic control. Looked at this way results for weight loss and gain were very different from previous studies.

They found prediabetic individuals were extremely susceptible to weight gain when consuming a high-glycaemic load diet, but saw substantial weight loss when consuming a diet with a low glycaemic load rich in whole grains, fruits, and vegetables – even without restricting calories.

Prediabetes is a condition in which blood glucose levels are higher than normal, but they are not high enough to warrant a diabetes diagnosis. However, people with prediabetes are at significantly greater risk of developing type 2 diabetes than those without prediabetes.

Likewise, diabetic participants lost more on a diet higher in healthy fats and plant-based foods and low in carbohydrates than they did on a low-fat and high-carbohydrate diet.

This is the opposite of individuals with normal glycaemic levels, who lost more on a low-fat and high-carbohydrate diet.

What this means is that both the low-fat and no-carb diets work – just not for everyone.

Personalised nutrition

The study’s results also show that personalised nutrition isn’t just a feel good concept but one that can make a significant impact in health and wellbeing.

And it is something that people and their healthcare providers can participate in now.

“Starting today, you can have your blood tested for a glucose level and if you are feeling very sophisticated your fasting insulin and with these two simple and accessible tests you can actually see what is best for you,” he said. “This is not something we need to wait ten years to use clinically. This is something we can start using today, and there are no adverse effects because it is not a medication. What we are doing is actually removing from your diet what would be harmful to you.”