6 weight loss facts
September 26, 2004
By Dr Norman Swan
Is the Atkins Diet any good? Are your genes hotwired to weight gain? In this extract from Health Minutes by Dr Norman Swan, we look at some of the hottest dietary dilemmas.
1. atkins diet - can 10 million people be wrong?
Ten million copies of the Atkin's Diet have been sold. This is not surprising, since nearly one in two women and one in three men are either dieting or thinking about dieting.
Doctors have slagged off at Atkins because of its high
fat content and restrictions on fruit and vegetables,
and it hasn't helped that the Atkins diet hasn't been
well studied. More recently, though, in a real-world
randomised trial, researchers compared the Atkins Diet
with a calorie-controlled low-fat diet. By "real
world" I mean that they tried to simulate how most
of us attempt to lose
weight - namely, by ourselves and without supervision.
At six months, the Atkins diet people had lost four per cent more than those on the regular diet - amounting to about 4kg less on board. They also had a greater rise in the good form of cholesterol (HDL) and a lower triglyceride (an unhealthy blood fat) reading. What didn't move on the Atkins Diet was the bad cholesterol - LDL. Both diets lowered blood pressure and made the body more sensitive to insulin.
After a year, though, nearly half the participants had dropped out and there was no significant difference between the groups. So Atkins may not achieve the Holy Grail of ongoing diet success, and no-one knows yet the long-term effects of eating little fruit and vegies.
2. are garlic and chilli weight loss foods in disguise?
There's growing evidence that populations with high garlic and chilli consumption have lower rates of obesity - these populations are mostly in Asian countries. That's after the higher levels of activity and lower levels of fat and energy substances are allowed for.
If it's true, just how do these substances work?
There's been a theory that chilli increases our metabolic rate - our energy consumption. That partly comes from the observation that chilli makes us sweat; there is also some evidence that it causes greater heat production in the body - a bit like caffeine.
When caffeine and chilli have been studied in real life, though, they seem to work by reducing appetite or making us feel full more readily rather than by boosting energy consumption. However, there is some evidence that chilli helps to break down fat by oxidising it.
One Dutch trial of chilli extract (capsaicin) aimed to see if capsaicin would assist with maintaining weight loss in a group of overweight adults. Researchers found that while there was added fat oxidation, there was no slowing effect on weight gain.
Garlic seems to reduce our fat and carbohydrate intake, which affects weight, of course. (Maybe the waiters stay away from us because of our breath.) Anyway, it's probably too early to make definite recommendations and we're twitchy enough as a society already without pushing caffeine-like substances even more. The place to start is more research into low-obesity communities so that we can tie down the reasons for that much more firmly.
Meantime, you can't do a lot of harm by asking for extra chilli on that stir fry - just beware of the sparks a few hours later.
3. maintaining weight loss
The statistics on keeping weight off once you've lost it are depressing. If you've been obese and return to the normal weight for your height, there's a 95 per cent chance your kilos will head north again. People who lose modest amounts of weight often do better, but most still stick it back on. Surveys of successful weight losers show that those who keep their weight under control do so because of the enormous amount of exercise they do: between 60 and 90 minutes a day.
A more practical question for non-dieters is how to slow down our inexorable rise in weight year after year. You see, our obesity epidemic comes from a pathetically tiny number of excess calories a day.
The problem is that, probably for genetic reasons, our appetite and eating are very hard to control. Even cutting out a few calories a day is tough, long term. The other answer is jacking up the energy expenditure. In the State of Colorado they've handed out those little wearable step meters (pedometres) and are challenging people to take an extra 2000 steps a day. So far, they know the meter helps in getting people to step up their exercise. Whether it holds back the weight is yet to be seen.
4. another obesity drug?
Researchers hoping to profit from our desire for thinness don't give up. You might recall hearing about leptin a few years ago. It's a hormone produced by fat cells which made fat rodents lose weight, and was supposed to be the answer.
A pharmaceutical company paid millions for the rights, but leptin hasn't panned out in most humans.
Now there's a new contender, with the code name SNAP. It blocks the effects of a brain hormone in areas which regulate appetite and food intake, and when given to rats which have eaten so much they've become fat, the doubtless grateful rodents lose weight.
SNAP seems to have other effects, though. When tested to see whether or not it changed other aspects of rat behaviour, they found that it did: it had an antidepressant and anti-anxiety effect. Apparently they can tell this from the way rats interact and swim when forced to.
The next step is to see whether humans will SNAP to attention the way these poor rats have.
I'll let you know.
5. big-boned in your genes
We're fat and getting fatter. We're hearing that ad nauseam; the question is, why?
You can only pin part of the blame on our environment. At least 40 per cent of our body weight is genetically determined. Most of us who veer to the pudgy have an insidious genetic network conspiring - in my case at least - to make us vacuum up the kids' leftovers.
British researchers have been trying to find single genes which might be at fault, and as a result they've found that there are folk who really can call themselves "big-boned".
They've tested about 800 families who have obese children, and discovered that five per cent have a defect in a gene called MC4R, or the melanocortin 4 receptor.
This is a lock and key mechanism for processes which control our metabolism, especially appetite. While MC4R children eat a lot and are obese, they're sometimes hard to pick, because in addition to carrying a lot of fat, they're tall and look strong - they have more muscle as well.
There are no treatments for NC4R yet, but people are testing possible medications. Mind you, I'm not sure where the front rows of school rugby teams will come from if the drugs work.
6. mental illness and your weight
There are links between obesity, the epidemic on everyone's lips at the moment, and mental health. But which way does it go?
Do fat people become depressed and anxious because they're fat, or does mental illness lead to obesity? And what role, if any, does weight loss play in restoring mental wellbeing?
An Australian study of 7000 people has not found a relationship between anxiety and depression and obesity at all. There was a slight connection in women between physical illness and obesity, though: for a given level of physical illness, it didn't matter to your mental health how fat your were, but being obese increased the risk of other diseases.
Then they adjusted for the effect of physical illness on anxiety and depression, and what bubbled to the surface then was that the men and women whose weight did tend to be linked to mental health were actually underweight. They had the worst mental health in the sample. Can't win, can you?
Anyway, it suggests that losing weight in its own right won't fix up your mental wellbeing; the only time it might would be if it alleviates your physical ailments along the way.
Source:www.news.com.au
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