Less protein makes you hungry, gorge on snacks

A team from the Cambridge University and the University of Sydney found that people whose meals contained 10 per cent protein consumed 260 more calories a day than those on 15 per cent protein.

Not only did they eat more but 70 per cent of the extra calories they ate were between snacks between meals rather than at mealtimes, the researchers found.

They also found that raising consumption to 25 per cent — as advocated by the Atkins Diet — was no extra help in halting over-eating, the Daily Mail reported.

“The results show that humans have a particularly strong appetite for protein, and when the proportion of protein in the diet is low this appetite can drive excess energy intake,” said lead author Alison Grosby of the University of Sydney.

For the study, the team recruited 22 volunteers, all of a healthy weight and aged between 18 and 51, to live and eat in a science facility.

While the foods looked the same, they had different protein levels. The amount of fat remained constant at 30 per cent of the total calories in a meal but the carbohydrate was adjusted to either 45, 50 or 60 per cent of the meal.

The volunteers all took the same amount of exercise — a one-hour supervised walk per day — and did the same activities to avoid them eating out of boredom or stress.

It was found that people who consumed 10 per cent protein a day ate on average an extra 1,036 calories over a four-day period compared with those who ate a 15 per cent protein diet. Over a year that would be enough to gain two stone (over 6kg), but eating more than the average amount of foods such as meat, fish, eggs and nuts can stop you gaining those kilos, the team reported in the journal PLoS One.

Each volunteer was asked to rate how hungry they felt at one-hour intervals and those who ate 15 per cent protein felt fuller two hours after a meal than those on the 10 per cent protein diet. But those on 25 per cent protein diet said the difference was no higher.

For weight loss, nutritionists recommend arranging your plate so a quarter of your food is protein, a quarter is carbohydrate and half is vegetables.

Co-author Dr Susan Jebb, head of the Human Nutrition Research Unit at Cambridge said: “Eating a large amount of carbohydrate and fat, such as in fizzy drinks are a major risk factor for obesity and they dilute your protein content, so there is a case for a modest increase, although we are not advocating eating huge amounts of protein or cutting out carbohydrates altogether.

“If what we found translates into the real world a 15 per cent protein intake would certainly be enough to prevent people over-consuming and help them lose weight.”