Crisis? No issue when it comes to diets – after all they have uninhibited high season for decades. The list of ways on how to get the ideal weight is getting longer: Some rule out any fats, others recommend large amounts of proteins and – don’t touch carbon hydrates. But not just the “yo-yo” effect makes clear – with the scale’s finger going to the right with no mercy – how little those plenty of methods are worth.
In defiance of all semons of the diet-gurus: The composition of what we serve ourselves every day has absolutely no relevance for reduction of weight. It is irrelevant whether the calories are coming from fats, proteins or carbon hydrates. The only thing that will show on the scale is the actual amount of calories we ate. If it’s less than the body needs the kilos will vanish. But if it’s more they will insistently get more and more. So what really counts is the energy balance. This frequently presented thesis now is being undergirded more clearly than ever before. The quality of the latest data from the US is considered as very high – also by experts beyond the Atlantic – and as more reliable than earlier surveys. Up to now there was a deficit of evidence regarding the efficiency of different diets – results of scientific studies were inconsistent and often contradictory. There was a lack of studies with numbers of participants high enough and over a sufficiently long time. This gap was closed by the recently published US-study.
Better eat half
The central question of this study was whether the preference given to fat, proteins or carbon hydrates might beneficially influence weight reduction – overweight people merely profiting from a specific combination of nutrients. For this purpose they put 811 overweight people on four different diets and examined the process of their loss of weight over two years. The participants of the study were age 30 to 70 and had a Body Mass Index (BMI) between 25 and 40. 40 percent were men – a novelty in diet studies. Exclusion criteria were for example type-1- and Type-2-diabetes, cardiovascular disorders and taking drugs influencing the body weight.
The diets were composed as follows: 20 percent fats, 15 percent proteins and 65 percent carbon hydrates as well as 20 percent fats, 25 percent proteins and 63 percent carbon hydrates. This low fat but high carb food was given to two groups of test persons during the entire study period. The other two groups ate – as a comparison – high fat and low carb with 40 percent fats, 15 percent proteins and 45 percent carbon hydrates respectively 40 percent fats, 25 percent proteins and 35 percent carbon hydrates. Each of those diets supplied 750 kilocalories less than used up daily.
The first outcome of the study was the change of body weight after those two years. The second target parameter was the change in the abdominal girth. It is common knowledge that the “belly-emphasizing” overweight is considered an independent risk factor.
After six months the participants were weighted for the first time. The four groups had lost an average of six kilograms weight. This loss was equally distinct in all test persons thus being independent from the respective diet. The US-scientists were presented with the same picture at the end of their study. The loss of weight remained comparable in all of the four different combinations of nutrients. Whether 15 or 25 percent proteins – the average loss of weight after two years was 3.3 kilograms. Also between the low fat diet with 20 percent and the high fat with 40 percent of fats there was no difference between the two groups with 3.3 kilograms: Just like with the carbon hydrates: Both the people in the group with 35 percent and the one with 65 percent carbon hydrate shares in their nutrition showed 3.2 kilograms loss of weight at the end of the study. The abdominal girth did not show any significant difference in all groups.
Those results confirm that the specific composition of a calorie-reduced nutrition does not have any influence on the loss of weight. Merely the daily eaten number of calories is clinically relevant. In other words and now scientifically confirmed: If the energy output is higher than the energy input – you will lose weight. Reversed you will gain weight. So better eat half to get that “Perfect 10”?
No carte blanche to feast
The US-scientists certainly do not want their results to be interpreted as a carte blanche to eat uncontrolled. Even if the combination of the diet does not show on the scale – it makes a difference for your health how many percent of fats, proteins and carbon hydrates are on your plate. For the study participants with low fat-high carb diet for example the LDL-values reduced with five percent more than for those with high fat-low carb by only one percent. And the HDL-cholesterol again increased by nine percent with a low carb diet compared to a high carb by six percent. The serum insulin level as well dropped only six percent versus twelve percent in the other group.
And better not forget what else the study discovered: Just like the body weight, the dreaded “yo-yo” effect does not care about »low fat« or »low carb« or vice versa. Because – despite the nutrition counselling on a regular basis – the participants gained weight again during the study. In all groups, i. e. with all four different diets, the weight of the people reduced for about 6 kilograms after six months. At the end of the study two of the people had returned to their old measures. There is no cure yet against this dilemma as well…