Een effectief dieet*
Wetenschappers van het Schotse onderzoeksinstituut Rowett hebben in een studie vastgesteld dat een dieet met weinig koolhydraten zeer effectief is in het bestrijden van het hongergevoel en voor het meeste gewichtsverlies zorgt. Het Rowett instituut is een onderzoekscentrum om de kwaliteit van voeding te vorderen en daardoor ziektes te bestrijden. In de studie kregen mannen met overgewicht een dieet bestaande uit veel eiwitten (30% van de totale calorieën) verder bestond het dieet of uit weinig (4%) koolhydraten of uit een gematigde hoeveelheid (35%) koolhydraten. Iedereen vond het eten smakelijk doch vooral de groep met de weinig koolhydraten
had veel minder honger dan de groep met de matige hoeveelheid. In 8 weken tijd verloor de weinig koolhydraten groep gemiddeld 6,3 kg per persoon en de andere groep gemiddeld 4,3 kg. Omdat uit een eerdere studie gebleken is dat koolhydraatarme
diëten het aantal van bepaalde bacteriën in de darmen flink doet afnemen zal nog verdere studie nodig zijn om te kijken of een dergelijk dieet voor iedereen en ook op langer termijn goed is.
Most Effective Weight Loss Diet Revealed
Scientists at Aberdeen's Rowett Research Institute have shown that a high protein, low carbohydrate diet is most effective at reducing hunger and promoting weight loss, at least in the short term. Their work has just been published in the American Journal of Clinical Nutrition.
Healthy, obese men were given two different diets during their stay in the Rowett's specialised Human Nutrition Unit. Both diets had a high protein content (30% of total energy value of the diet) but they differed in the amount of carbohydrate: One diet was low in carbohydrate (4%) and the other contained a moderate amount of carbohydrate (35% total energy value).
"Our volunteers found both diets to be equally palatable, but they felt less hungry on the high-protein low-carbohydrate diet compared with the diet which contained high-protein but moderate amounts of carbohydrate," said Dr Alex Johnstone, the Rowett's weight-loss expert who led the study.
"Weight loss during the two four week study periods was greater on the high-protein low-carbohydrate diet, averaging 6.3 kg per person, compared with 4.3 kg on the moderate carbohydrate diet," said Dr Johnstone.
An important part of this study was to unravel the physiological mechanisms behind this type of diet. It is known that when people eat low carbohydrate diets, within a relatively short time their body has to switch from using glucose as a fuel to using something different called ketone bodies. Ketone bodies are appetite-suppressing and they may have an effect on the appetite centres in the brain. It's also well known that protein itself is very good at making people feel
full-up.
"In this study, we showed that on the high-protein low-carbohydrate diet the volunteers became ketogenic within 1-2 days of starting this diet and so it may be that high-protein, low-carbohydrate diets are particularly effective because of the combined effect of the protein and the ketone bodies," said Dr
Johnstone.
"We showed that the volunteers on the ketogenic diet reduced their energy intake without increasing their hunger and this was a very important factor in their ability to stick to the diet."
Dr Johnstone sounds a note of caution about her findings: "A paper published last year from the same study showed that low carbohydrate diets may have consequences for the health of the gut by dramatically reducing the numbers of particular types of bacteria. So we will be looking in more detail at the complex way in which we respond to changes in our diet before we can say whether low-carbohydrate ketogenic diets are a suitable tool for everyone who wants to lose weight."
When the phase of the study which involved the volunteers finished in October 2004, it attracted considerable interest because of its celebrity volunteer, Cameron Stout, who lost just over 12 kg during his nine week stay at the Rowett Institute. At the time, Cameron mentioned his surprise at not feeling hungry during the study and said he had adjusted to eating smaller portions. How does he feel now, three years later?
"I had a great experience with the nutrition study at the Rowett. The food was excellent and the staff looked after us very well. Because I have such an irregular lifestyle I don't find it easy to stick rigidly to all that I learnt while I was at the Institute, but I try to make an effort most of the time. For me it was mainly about breaking bad habits and I guess we all have food vices we need to deal with!" said Cameron.
ROWETT INSTITUTE
Greenburn Road, Bucksburn
Aberdeen AB21 9SB
http://www.rowett.ac.uk (Februari
2008)
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