Why it’s protein, NOT carbs, that makes you gain weight – and how to stop it, revealed by top scientists

Carbohydrates are seen by many as ‘the enemy’ of a healthy body weight. The mantra ‘no carbs before Marbs’ (from TV show The Only Way Is Essex – about holidaying in Marbella) reflects the widespread view that carbs lead to fat gain.

This is based on the fact that carbohydrates – such as bread, potatoes, pasta, cakes and biscuits – are broken down in the body into glucose – which can increase blood sugar levels; Over time, this can lead to weight gain and health problems, such as type 2 diabetes and heart disease.

But has our understanding of this been wrong?

A study published in the journal Cell Metabolism suggests that in some people it is fat and protein, not carbohydrates, that cause high blood sugar. Levels are generally controlled by insulin, a hormone produced by beta cells in the pancreas that helps cells clear glucose and use it for energy.

Insulin also helps the body store extra glucose in the form of glycogen, mainly in the muscles and liver (it is then returned to the blood when blood sugar levels are too low).

Testing blood sugar levels at home with a glucometer is often performed by people with diabetes or at risk of diabetes

But when the cells stop responding to insulin, excess glucose circulates in the bloodstream.

The pancreas then pumps out more and more insulin to keep blood sugar levels low – until it can no longer keep up, causing type 2 diabetes. Over time, high blood sugar levels damage blood vessels and nerves.

In the latest study, scientists from the University of British Columbia in Canada took 140 pancreatic islets (clusters of pancreatic cells including beta cells) from deceased human donors with and without type 2 diabetes.

They also took pancreatic islets made from stem cells (“master cells” that can form different types of cells in the body). The experts then looked at how much insulin they secreted in response to carbohydrates, proteins and fats.

The study showed – for the first time – that some islets in the human pancreas produced more insulin in response to fatty acids (fats) and amino acids (proteins) compared to glucose (carbohydrates). This turned traditional thinking upside down.

Could this change the advice given to some people?

“It’s an interesting concept and it may provide some explanation for the variability we see in the extent to which people respond to specific diets – for example, low-carb diets – so we know there is no one size fits all,” says Dr Efthimia Karra, consultant endocrinologist at the Royal Free Hospital and Princess Grace Hospital, both in London.

Aisling Pigott, a dietitian with a special interest in diabetes for NHS Wales, says: ‘In the clinic we see [from glucose monitors] that some people experience an increase in glucose from carbohydrates and that others may respond more to proteins and fats. It depends on the individual and the amount they ate.”

No carbs before Marbs was the mantra of some stars on the TV show The Only Way Is Essex

She says the research results confirm that no two people are the same in the way they respond to food and that metabolism is complex.

“It could help alleviate the guilt and frustration that some people with diabetes feel when they work hard but fail to lose weight and improve their blood sugar levels,” she adds.

A high-fat diet may not necessarily be the solution, as it can cause fat to accumulate around the abdomen. This type of fat increases inflammation in the body, making cells less responsive to insulin.

This latest research has implications for countries like Britain, where our diets are often high in carbohydrates, says Roy Taylor, professor of medicine and metabolism at Newcastle University, who helped develop a low-calorie diet that has been shown to reduce the type 2 causes. diabetes in remission.

It involves the use of meal replacement soups and shakes for the first 12 weeks (totaling between 800 and 900 calories per day).

Professor Taylor says there is a place for carbohydrates in our diets, but the added calories are the problem. “It’s so easy to overeat a pile of mashed potatoes or consume too much pasta or rice,” he adds.

Furthermore, having too many carbohydrates can cause different reactions in the body depending on how sensitive you are to insulin, explains Professor Taylor. “If you have normal insulin sensitivity, your breakfast cereal will go towards your muscle glycogen stores, but if you don’t, the body immediately converts much of that glucose into fat.”

Everyone has a different sensitivity to insulin, dictated by genes.

It may not be clear whether you are insulin resistant, so it’s worth looking at your family history. If a family member has had a heart attack or diabetes, consider cutting back on carbohydrates, says Professor Taylor.

This is because if you are insulin resistant and excess carbohydrates are stored as fat, it can lead to clogged arteries, increasing your risk of heart attack or stroke.

Professor Roy Taylor says it may not be obvious that you are insulin resistant

But this can be adjusted to a small extent through regular exercise and weight gain or loss.

Other factors, such as aging and hormonal changes, can influence our response to food, adds Aisling Pigott, who is also a spokeswoman for the British Dietetic Association.

‘For example, when women are perimenopausal and menopausal, their estrogen levels drop, which affects their muscle maintenance, so they may have a higher percentage of body fat than before, and we know this increases resistance to insulin.’

Likewise, the stress hormone cortisol can stop insulin from working as well as it should.

When it comes to the latest research, experts agree that more studies are needed to find out if this translates to humans. As Professor Taylor says: ‘It is important to note that some of the results of the study related to the length of time the islets were cultured in the laboratory. [the longer they were in the lab, the more time they had to secrete insulin, meaning higher amounts] – it is so far removed from the situation in real, living people.

‘Type 2 diabetes is a stunningly simple disease; people on the path to diabetes have usually become too heavy for their own bodies,” he adds.

‘Keep in mind that any weight gain in adulthood is made up exclusively of fat. We don’t naturally grow extra muscle, bone or brain tissue, so people’s weight in middle age should actually be the same as they were in their twenties.’

His views resonate with Dr. Karra: ‘Ultimately the most important message remains that you need to keep your weight at a healthy level and it may take some trial and error to find the best diet that achieves this for you .’

And in the short term, there is some simple but important advice. As Aisling Pigott explains: ‘It’s essential to be active within an hour of eating a meal.

‘This can greatly reduce the rise in glucose levels after meals, because when we exercise our cells take up glucose for energy, and it increases the impact of the insulin we have, reducing our cells’ resistance to it.’

She adds: ‘This doesn’t have to mean going to the gym – a gentle walk or just tidying up the kitchen can help – but it’s really helpful to avoid standing still around this time.’