Monday, March 05, 2007

Protein and weight control

The eating habits of locusts and caterpillars might hold the key to discovering the perfect diet, researchers say. At the University of Sydney, obesity experts are conducting a three-year trial that aims to prove people keep eating until they have satisfied their appetite for protein. The study will involve groups of volunteers kept in laboratory conditions for a week at a time and fed carefully manipulated diets. The project's chief investigator, Professor Stephen Simpson, said the study will test his "protein leverage hypothesis" that high-protein diets, such as the CSIRO Total Wellbeing and Atkins, work not because they cut out carbohydrates but because they are high in protein.

The theory follows the observation that insects such as locusts move in swarms to areas providing enough protein for their diet. Humans don't move, they eat more. "If you eat a diet with a high proportion of fat and carbohydrates - the typical modern Western diet - you will keep eating until you get the amount of protein the body needs before you feel full," Professor Simpson said. "And that means you will grossly overeat."

The researchers will soon begin recruiting volunteers - 24 lean and 24 obese - who will live in a special unit at Royal Prince Alfred Hospital for three periods of one week. Monitored 24 hours a day by research staff, the volunteers will be given a low, medium or high protein diet and the amount they eat and their weight will be measured. "In the week they eat a high-protein diet they should eat fewer calories," co-researcher Professor Ian Caterson said.

The discovery comes as Israeli scientists have stumbled on a "super pill" that helps people lose weight at a staggering rate. The drug, betahistine, has been used for years to treat balance disorders such as vertigo. It is now being trialled on 280 people in the US and Canada to investigate its effect on weight loss. In a pilot study in Israel, 20 volunteers shed 1.8 kilograms a week for three months while taking the drug, which is thought to affect appetite by interacting with histamine receptors in the brain, reducing the desire for food, particularly fatty meals. British reports say the drug is expected to be fast-tracked by British and US drug safety regulators and should be available for treating obesity in 2009.

But Deakin University's Professor of Population Health, Boyd Swinburn, said the drug "won't be a magic bullet". The average weight loss attributed to such medication was only two to three kilograms and significant weight loss came from major lifestyle and behaviour changes.



The Atkins diet arouses strange passions. For background, see here

A scientific study into the controversial Atkins diet suggests that it can be one of the most effective ways for women to lose weight. At the end of 12 months, overweight subjects on the Atkins regime had lost twice as much weight on average as women on three competing diets. Atkins minimises carbohydrates, such as bread and sugar, in favour of meat and other proteins.

However, amid increasing concern that its devotees miss out on vital nutrients, it has recently been supplanted by new regimes such as the GI diet, which consists of foods that release glucose slowly and evenly into the bloodstream. This week, however, the study will say Atkins produced more weight loss with no signs of undesirable side-effects. "So many people have been asking questions about diets for years. We think it's time to give them some answers," said Christopher Gardner, professor of medicine at Stanford University's disease prevention research centre in California, who led the study. "We have an epidemic of obesity that's still on the rise, and the ideas of our best and brightest people haven't been able to change that."

In the study, 311 pre-menopausal, overweight women were asked to follow one of four regimes: the Atkins, Zone, Learn or Ornish diet. Each involve a different level of carbohydrate intake. The Atkins diet recommends the lowest level, the Zone diet a little more. The Learn (Lifestyle, Exercise, Attitudes, Relationships and Nutrition) diet follows the American government's recommendations for a diet low in fat and high in carbohydrates. The Ornish diet is very high in carbohydrates and extremely low in fat.

After a year, the 77 women in the Atkins group lost an average 10lb - about twice as much as those on the Learn and Ornish diets. Women on the Zone lost an average of 3.5lb. Women in the Atkins group also achieved larger reductions in body mass index, triglycerides and blood pressure - all signs of improved health.

Susan Jebb, head of nutrition and health research at the Medical Research Council, said the reason for Atkins's success was that people found a diet that allowed high intakes of meat and fat easier to follow than other more spartan regimes. In Britain, the Atkins diet reached its peak popularity around 2003 when a survey indicated that 3m people were on it. It was endorsed by celebrities such as Jennifer Aniston. Its popularity has since waned.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.