[ad_1]
When it comes to dieting, research shows that the majority of people will regain some, if not most, of the weight they lost. While there are many reasons why this weight gain can happen, some popular claims online are that it is because the diet is definitely destroying your metabolism. But while it’s true that a diet slows down your metabolism, it also improves your metabolism in a number of positive ways.
When we talk about metabolism, we are generally referring to your metabolic rate. This is the number of calories your body burns while at rest. Of course, the more activity we do, the more calories we burn. In order to lose weight through diet, you need to consume fewer calories than you use. This forces the body to use its energy reserves – like fat – to make up the deficit. Your metabolic rate will also change accordingly.
Losing lean tissue (muscle) when you diet – which burns around 15 to 25 calories per kilogram each day – lowers your resting metabolic rate, which means you need fewer calories than before. But the body also deliberately slows down the metabolism to conserve energy stores and minimize weight loss.
When the body senses depleted fat stores, it triggers adaptive thermogenesis, a process that further lowers the resting metabolic rate – and can slow weight loss despite strict diet. Adaptive thermogenesis can occur within three days of starting a diet and it is suggested to persist well beyond a diet – even when hindering weight maintenance and promoting weight gain.
An example of the effect of adaptive thermogenesis was seen in a widely publicized 2016 study that looked at former contestants for the American reality show. The biggest loser. It showed that participants had a significant decrease in their metabolic rate even several years after the initial weight loss. Participants were required to consume up to 500 calories less than expected per day.
Other studies have also shown metabolic slowing with weight loss, but with much smaller decreases (about 100 calories less per day to maintain weight). However, it is less certain that this slowdown will persist once the weight is stable.
Research seems to show that most adaptive thermogenesis occurs in the dieting phase as a temporary response to the amount of weight lost. Overall, we do not have conclusive evidence to support the notion that the metabolic rate remains slowed in the long term (more than a year after the diet).
It should be noted that there are many factors that can affect the metabolic rate, so the changes made after a diet can vary from person to person. For example, a study of fasting diets showed that the metabolic rate decreased as a result – but those with the greatest decrease in metabolic rate already had a higher metabolic rate, to begin with. Overestimating metabolic rates at the start of a study or errors in predicting metabolic rate after weight loss could also affect study results.
It is understood that the metabolic rate slows down due to weight loss, both due to the decrease in body size and as a way to preserve key tissues and fuel stores. But there is currently no consensus on the slowdown. Quantifying and predicting this slowdown is currently being researched at the University of Surrey.
Metabolic changes
A decrease in metabolic rate, however, is just one change that occurs with weight loss.
When we lose weight, the main change we see is a decrease in body fat. This decrease is actually the reduction in the size of our fat cells – they don’t actually go away. This shrinkage of fat cells indicates that the body’s fuel reserves are being depleted, causing the hormone leptin to drop. Usually, leptin suppresses appetite and increases metabolic rate – but when leptin levels drop, metabolic rate slows down and hunger increases.
The gut also releases less incretins (hormones that regulate appetite) when we lose weight, which may linger beyond diet. Less leptin and less incretins can make us feel hungry and lead to overeating.
When fat cells shrink, they can absorb glucose and store fat more efficiently to help restore lost fuel. Your body also creates more fat cells so that you can store more fat in the future to better cope with this calorie “crisis” the next time it occurs.
But as contradictory as it sounds, all of these changes actually lead to a more efficient and ultimately healthier metabolism. For example, smaller fat cells are better for our health, because over-swollen “sick” fat cells don’t work as well to get rid of excess fat and sugar. This can lead to high levels of sugar and fat in the blood, increasing the risk of insulin resistance, diabetes, and cardiovascular disease.
So dieting doesn’t technically ruin your metabolism, but rather improves it by helping it function better. But without care, this metabolic boost can conspire against you to gain weight, and even exceed your initial weight.
Studies show that exercise (or just physical activity) can be a way to prevent weight gain, by improving our ability to maintain our weight and can potentially minimize metabolic slowdown. Exercise can also help regulate appetite and fuel burn in the short term and may make weight loss more sustainable in the long term.
This article was originally published on the reversesure by Adam collins and Aoife Egan at UCL. Read it original article here.
[ad_2]
Source link