Protein key to curbing overeating and preventing obesity

October 18, 2011

(Medical Xpress) -- Including enough protein in our diets, rather than simply cutting calories, is the key to curbing appetites and preventing excessive consumption of fats and carbohydrates, a new study from the University of Sydney has found.

A multi-disciplinary team of researchers has shown that people on a 10 percent diet will eat more snacks between meals and consume significantly more calories in total compared with people on a 15 percent protein diet.

The results, published in the online journal PLoS ONE, represent the first scientifically supported evidence that plays an important role in appetite and total in humans, and are an important step in addressing the global .

"Humans have a particularly strong appetite for protein, and when the proportion of protein in the diet is low this appetite can drive intake," said lead author Dr Alison Gosby, who conducted the study with Professor Steve Simpson from the School of .

"Our findings have considerable implications for body weight management in the current nutritional environment, where foods rich in fat and carbohydrates are cheap, palatable, and available to an extent unprecedented in our history."

Protein is the driving force for appetite in many animals, according to Professor Steve Simpson, a world leader in nutrition. The 'protein-leverage' hypothesis, first proposed by Steve Simpson and co-author David Raubenheimer, proposes that animals have a fixed protein target, which they will defend at the expense of other nutrients.

"Our previous work on slime moulds, insects, fish, birds, rodents, mink, cats and monkeys has shown that animals have separate appetites for protein, fat and carbohydrate. Interestingly, if protein in the diet is diluted, even by a small amount by extra fat and carbohydrate, the appetite for protein dominates and they will keep eating in an attempt to attain their target level of protein," he says.

Although it has previously been suggested that protein content plays an important role in determining overall energy intake in humans, and is therefore linked to obesity, until now experimental verification has been lacking.

In their new study Dr Gosby and Professor Simpson wanted to test the 'protein-leverage' effect in humans. The researchers created three menus that represented low (10 percent), intermediate (15 percent) and high (25 percent) protein, based on data from the World Health Organization recommending people eat 15 percent protein diets. With the exception of protein, the three diets were identical in all other factors such as appearance, palatability, variety and availability.

The researchers then took a group of 22 lean people and fed each subject each of the three menus during three separate four-day periods, monitoring energy intake over each four-day period and hunger ratings on day four.

The researchers found subjects who ate a 10 percent protein diet consumed 12 percent more energy over four days than those eating a 15 percent protein diet. Moreover, 70 percent of the increased on the lower protein diet was attributed to snacking.

When the protein content was further increased to 25 percent, however, the researchers observed no change in behavior relative to the 15 percent . On the fourth day of the trial, however, there was a greater increase in the hunger score between one to two hours after the 10 percent protein breakfast versus the 25 percent protein breakfast.

Dr Gosby commented: "This result confirms the 'protein-leverage' effect in humans and importantly, shows counting calories is not enough to manage appetite and body weight. In the western world, where food is abundant, if you reduce your calorie intake but fail to reach your protein target you will find it hard to resist hunger pangs."

Professor Simpson says today's western-world diets - where protein is increasingly diluted by fats and carbohydrates - are likely to be causing us to overeat and could be fueling the obesity epidemic.

"Our results indicate low protein diets will cause humans to overeat. Tragically in the modern westernised environment there are many factors encouraging us to eat foods that are high in sugars and fat, including reduced cost and increased availability of these foods. Underpinning all this is our ancestral environment in which fat and simple sugars were highly prized, leaving us with a predilection for these foods."

Explore further: Testing protein leverage in lean humans: a randomised controlled experimental study

Related Stories

Testing protein leverage in lean humans: a randomised controlled experimental study

October 12, 2011
Proper protein intake crucial for moderating energy intake, keeping obesity at bay.

Eat a protein-rich breakfast to reduce food cravings, prevent overeating later, researcher finds

May 19, 2011
A University of Missouri researcher has found that eating a healthy breakfast, especially one high in protein, increases satiety and reduces hunger throughout the day. In addition, using functional magnetic resonance imaging ...

Low-carbohydrate, high-protein diets may reduce both tumor growth rates and cancer risk

June 14, 2011
Eating a low-carbohydrate, high-protein diet may reduce the risk of cancer and slow the growth of tumors already present, according to a study published in Cancer Research, a journal of the American Association for Cancer ...

Recommended for you

Dog walking could be key to ensuring activity in later life

July 24, 2017
A new study has shown that regularly walking a dog boosts levels of physical activity in older people, especially during the winter.

Alcohol to claim 63,000 lives over next five years, experts warn

July 24, 2017
Alcohol consumption will cause 63,000 deaths in England over the next five years – the equivalent of 35 deaths a day – according to a new report from the University of Sheffield Alcohol Research Group.

App lets patients work alone or with others to prevent, monitor, and reverse chronic disease

July 24, 2017
Lack of patient adherence to treatment plans is a lingering, costly problem in the United States. But MIT Media Lab spinout Twine Health is proving that regular interventions from a patient's community of supporters can greatly ...

Alcohol boosts recall of earlier learning

July 24, 2017
Drinking alcohol improves memory for information learned before the drinking episode began, new research suggests.

To combat teen smoking, health experts recommend R ratings for movies that depict tobacco use

July 21, 2017
Public health experts have an unusual suggestion for reducing teen smoking: Give just about any movie that depicts tobacco use an automatic R rating.

High-fat diet in pregnancy can cause mental health problems in offspring

July 21, 2017
A high-fat diet not only creates health problems for expectant mothers, but new research in an animal model suggests it alters the development of the brain and endocrine system of their offspring and has a long-term impact ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.