A team of European researchers confirms what many weight-loss gurus have claimed: eating more protein and fewer refined carbohydrates helps to keep the pounds off.
Among men and women who had lost at least eight percent of their body weight on a low-calorie diet, those who spent the next six months following a maintenance diet high in protein and low in refined carbs were the least likely to regain any weight, and were also the least likely to drop out of the study.
So is this something you can try at home? Maybe. Participants were divided into groups eating varying amounts of protein, a moderate amount of fat, and different quantities of carbs categorized as either high or low on the glycemic index, a measure of how fast a food is converted to sugar in the blood.
Whether the study results “translate into different dietary advice for more broad use probably still has to be discovered because glycemic index is really not an easy and straightforward tool to use for most people I would say,” Dr. Thomas Meinert Larsen of the University of Copenhagen, one of the study’s authors, told Reuters Health.
The glycemic index, GI for short, was originally developed for use by diabetics, and indicates how quickly blood glucose peaks after a person eats a particular food. High-GI foods, like white bread, produce a quick spike in blood glucose, while low GI foods, like whole grain breads, cause a slower increase in blood sugar that lasts for a longer period of time. Most food labels don’t list a food’s GI, nor is there adequate information on the GIs of different foods available on the Internet, according to Larsen.
Whole grains
In the new study, published in The New England Journal of Medicine, Larsen and his colleagues initially enrolled 773 men and women and their families in eight different western European countries. Families were randomly assigned to one of five different weight-maintenance diets for 26 weeks. None restricted calories, but four of the diets did dictate the proportion of proteins, fats and refined carbs that should make up daily food intake.
One group with no food restrictions served as a control, the rest were assigned to eat either a low-protein, low-GI diet; a low-protein, high-GI diet; high-protein and low-GI; or high-protein and high-GI. In the low-protein groups, people consumed 13 percent of calories as protein; in the high-protein groups, 25 percent of total energy consumed was protein. People in all of the groups could eat as much as they liked.
Seventy-one percent of the adults enrolled in the study completed it. While around 26 percent of people in the high-protein or low-GI groups dropped out of the study, 37 percent of people in the low-protein, high-GI group quit.
Among the 548 people who completed the study, only those who ate a low-protein, high-GI diet gained a significant amount of weight (1.67 kilograms, on average, or about 3.7 pounds). When the researchers looked separately at people in the high-protein diet groups, they found these individuals gained about a kilogram less than those in the low-protein groups; the same was true for the low-GI versus high-GI groups.
Larsen pointed out that people should use common sense in applying the low-glycemic principle. The hazelnut-chocolate spread Nutella actually has a lower GI than boiled carrots, he noted, although it obviously isn’t the healthier food; for this reason, he said, people should use the GI concept within food groups, for example choosing whole grain instead of white bread, or brown rice versus white.
Brown rice.
While anyone can slash their calorie intake and lose weight short-term, the hard part is keeping it off, says Dr. David Ludwig, the director of the Optimal Weight for Life Program at Children’s Hospital Boston. The fact that people in the high-protein, low-GI diet were the most successful suggests that keeping weight off doesn’t have to be a matter of sheer willpower, added Ludwig, who co-authored an editorial accompanying the study.
“The nature of the diet and how that diet affects our underlying biology may have a lot to do with how likely we are to comply, to remain on the diet,” said Ludwig. People on the high-protein, low-GI diets “appear to like this way of eating more, perhaps because they were feeling less hungry and more energetic…or just noticing that they were doing better. There’s nothing that succeeds like success when it comes to weight loss.”
According to Ludwig, people can definitely try this at home. “Adding a serving of nuts and beans to the diet every day and cutting back on the refined grains will produce at least as much dietary change as they obtained in the study,” he said. “If everyone in America could cut back on two servings of refined grains and substitute that with one serving of nuts and one serving of beans, the impact on public health would really be potentially enormous, and that’s a change within everyone’s reach.”
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Protein-rich diets containing lots of lean meats, fish and egg – as popularised by the Atkins diet – are the best at keeping weight off, according to the world’s largest study of its kind.
But dieters should also combine that with eating lots of wholegrain cereals and fresh fruit and vegetables, researchers have found.
People who stick to this approach can simply eat until they feel full and not put on weight, according to the Danish nutritionists. Their research is published in the New England Journal of Medicine today (THUR).
They asked 938 volunteers to go on a strict 800 calorie-a-day diet for two months. Then they split them up into five groups, each following a different low-fat diet aimed at maintaining their weight.
However, only those who stuck to the high protein, low glycemic index (GI) diet managed to stop putting any weight back on over the following six months. On average, the others put on 0.5kg (1.1lb). Those on the worst-performing regime – a low protein, high GI diet – put on almost 2kg (4.4lb).
Prof Arne Astrup of Copenhagen University, who headed the pan-European Diogenes study, explained why the high protein, low GI diet worked best.
He said: “It’s simply due to satiety – of what gives a feeling of more fullness.”
Protein-rich foods resulted in “a greater release of satiety hormones” than othertypes, he explained.
“You simply stop eating after you have consumed fewer calories than with the other diets.”
But consuming low GI carbohydrates was also important.
These are foods like wholegrain cereals that the body takes longer to digest, resulting in blood glucose levels rising and dropping more gradually.
These tend to suppress appetite for longer, in contrast to high GI foods like mashed or baked potato or sugary cereals, which cause rapid rises and falls in blood sugar levels.
The researchers recommended lean meat, poultry, fish, eggs, low-fat dairy products, beans and nuts as good sources of protein.
Besides wholegrain cereals, they also said pasta cooked ‘al dente’, new potatoes – preferably cooled down – and basmati rice were good sources of low GI carbohydrates.
Although the study involved obese adults, with an average body mass index of 34, Prof Astrup said the principles behind the diet applied “absolutely” to people who were healthy or only slighty overweight.
The Atkins diet, which millions tried at its peak in 2004 following praise from personalities including the actress Jennifer Aniston, is itself based on the principle that high protein foods make one feel full sooner.
But Prof Astrup emphasised: “This diet is far away from Atkins.”
While 50 per cent of calories come from protein under Atkins, he said with their diet the percentage was just 23.
And while under ‘low-carb’ Atkins as little as 10 per cent of calories come from carbohydrates, in their diet the figure was 45 per cent.
Thomas Meinart Larsen, who also worked on the study, explained why new potatoes were best served cold.
“This is due to the chemical structure of the carbohydrates when cooled down,” he said. “Therefore they are broken down more slowly in the intestines.”
As every dieter knows, losing weight is the simple bit. Keeping it off is the real challenge.
Now the world’s largest diet study has come up with a solution: the most effective way of maintaining weight loss is to eat a high protein/low glycaemic index (GI) diet, with lots of lean meat, beans and low-fat dairy products and fewer foods high in refined starch such as white bread and white rice.
The glycaemic index applies to carbohydrates and is a measure of how fast they are converted to glucose. The lower the GI, the slower the digestion and the greater the level of satiety.
Low GI diets allow people to eat until they are full, without counting calories and without gaining weight.
An international study of more than 900 adults and 800 children from eight European countries – including the United Kingdom – found that after six months those on the diet were on average 2kg lighter than those on rival diets with a high glycaemic index. The participants had already lost an average of 11kg and were testing alternative approaches to maintaining their weight loss.
Professor Arne Astrup of the University of Copenhagen, who led the study, said the findings suggested official dietary advice was out of date.
“I was one of the enemies of GI,” she said. “I expected in this trial it would make no difference. I was really surprised. It is as important as protein in maintaining weight loss.”
High protein diets, such as the Atkins, are known to promote weight loss, because they delay emptying of the stomach and increase insulin production.
Adding carbohydrates with a low glycaemic index which are digested slowly decreases hunger.
Motivation is key in maintaining weight loss and a high protein/low GI diet is easier to follow because no major food group is banned.
But following the diet poses its own challenge. Wholegrain breads and cereals are mostly low GI, as are most vegetables. Among fruits, apples, pears and oranges are low GI, but grapes, kiwi fruit and melon are high GI because they have a lot of sugar. Chocolate is low GI, as the fat slows absorption of the sugar. A hot baked potato has a high GI but cooling transforms the starch rendering it less easily digested, so it becomes low GI.
“If you choose wholegrain versions of bread, pasta and rice, then you will have a lower GI diet. These are the most important contributors,” Professor Astrup said.
Typical menu
Breakfast
Low-fat milk with muesli (any variety without added sugar), wholegrain bread with low-fat cheese, an orange
Lunch
Wholegrain bread with lean meat or chicken, tuna steak in tomato sauce with vegetables
Dinner
Stir-fried turkey with vegetables and wholegrain pasta; avocado salad with feta cheese and sugar peas.