Do herbal diet pills really work?
Obesity is expected to overtake smoking as the main cause of avoidable deaths in the next decade, according to a recent House of Commons report.
Many people find it hard to lose excess weight, so it's unsurprising that the market for slimming supplements is worth £50million.
Herbal slimming pills — claiming to be 'natural' — may sound particularly appealing. But do they work? It was reported last week that one supplement, Zotrim, helped people to lose weight even if they weren't dieting. But some experts are questioning the results.
Zotrim contains extracts of South American herbs (mate, guarana and damiana), and it is thought to make you feel fuller for longer after eating.
In one scientific study, ultrasound scans showed that people on Zotrim took 20 minutes longer to empty their stomach, making them feel more satisfied from their last meal.
The latest Zotrim research was presented at the British Dietetic Association's annual conference.
Independent dietician Dr Carrie Ruxton reported her findings on a study involving 87 health workers (mainly female) aged 18 to 70. Some 68 completed the study, losing an average of 2.1kg (4.6lb) in six weeks. They reduced their waist circumference by 3.6cm (1.4in). Most participants were obese before the study, with an average BMI of 30.58. After six weeks, their BMI fell to 29.58.
A month after the trial, Dr Ruxton reassessed the women. She said: "Most of them stabilised or lost more weight — about 1.5lb. A supplement such as Zotrim can boost a dieter's confidence and inspire them to make changes, both of which can help against obesity.
"However, a supplement pill should be seen only as an extra tool. For long-term weight control, a sensible diet and exercise programme must be the principal way."
So, is Zotrim the magic pill for which dieters have been waiting?
"The weight loss in this trial isn't significant as far as we are concerned," says Claire MacEvilly, a nutritionist from the MRC Human Nutrition Research in Cambridge.
You need to reduce body weight by 10 per cent to see any clinical effects such as changes in blood pressure, insulin sensitivity and triglyceride levels, which can increase the risk of diabetes, cancer and heart disease.
The fact that this trial saw a 2.6 per cent reduction of weight at week six and 3.3 per cent at week ten is, therefore, unimpressive.
"We did some research here where we just gave people some regular and intensive dietary advice and this resulted in a 10 to 12 per cent weight loss."
Dr David Ashton, medical director of The Healthier Weight Centre in Birmingham, points to the fact that the study participants continued to lose weight after finishing taking the supplement to suggest the weight loss was a placebo effect.
"Another problem is that we don't know what it was that the programme participants lost — losing fat, not water, is important."
What about all the other dieting pills in our supermarkets, boasting ingredients such as apple cider vinegar, fucus (seaweed) and green tea?
"The evidence behind these dieting pills is very weak, if not nonexistent," says Claire MacEvilly. "We haven't found any evidence for the effectiveness of ingredients such as apple cider vinegar."
However, she adds, green tea may be an exception, as a few studies from Japan suggest it may make people feel full.
Ultimately, it's calories that count — eat less and exercise more. "It would be better to spend the money on healthier foods such as fruit, veg and wholegrains," she says. |
