A diet that’s low on carbs – like the Atkins diet – is still regarded as an effective way to lose weight. If you react well to a low-carb diet, it might be a good idea to make this your permanent way of eating.
From an animal study, published by American nutritionists at Purdue University in Nutrition & Metabolism, you can conclude that you’ll put on weight more quickly if you start to eat ‘normally’ again after a few weeks on a low-carb diet.
The researchers did an experiment with rats, and divided their lab animals into two groups. One half got low carb type food for the first 8 weeks, and the other half were given standard food. After the 8 weeks, the low carb rats were put back on a normal diet. The other group’s diet remained the same. In week 16 the researchers looked at what effect the change back to normal food had had.
The Atkins rats had put on weight at a faster rate in the second half of the experiment. CH = rats that had standard food for sixteen weeks; KD = low carb diet; KD:CH = rats that had an Atkins diet for the first 8 weeks and then 8 weeks of standard food. The graph below shows that the rats in the KD:CH group put on weight faster.
The increased weight was in the form of fat mass. The figure below shows what happened to the epididymal fat reserves. This is a marker for the total fat mass.
The cause of the increase in bodyweight is simple. Rats that go from Atkins to standard food eat more.
The increased appetite of the rats that changed diet may be the work of the appetite hormone ghreline. Ghreline is released when your stomach is empty, and the production of this hormone is boosted by the changeover from low-carb to a standard diet.
The researchers are uncertain as to whether these results also apply to humans. One reason for their hesitation is the kind of food they used for the rats. Their low-carb food was also extremely high fat and therefore low protein. If people eat low carb it usually means they eat high protein.
Nevertheless the Americans draw a cautious conclusion. “The current data suggest that continued maintenance on a low carbohydrate diet may play a role in prevention of increased body weight and caloric intake.” Reducing carbohydrate intake helps keep weight under control – but you have to keep your carb intake low.
Effects of consuming a high carbohydrate diet after eight weeks of exposure to a ketogenic diet
Ketogenic diets have been utilized for weight loss and improvement in metabolic parameters. The present experiments examined the effects of returning to a chow diet after prolonged ingestion of a ketogenic diet.
Rats were maintained on chow (CH) or a ketogenic diet (KD) for 8 weeks, after which the KD rats were given access to chow only (KD:CH) for 8 additional weeks. Caloric intake, body weight, and plasma leptin, insulin and ghrelin were measured before and after the dietary switch.
After 8 weeks of consuming a ketogenic diet, KD rats had increased adiposity and plasma leptin levels, and reduced insulin, as compared to CH controls. One week after the diet switch, fat pad weight and leptin levels remained elevated, and were normalized to CH controls within 8 weeks of the dietary switch. Switching from KD to chow induced a transient hypophagia, such that KD:CH rats consumed significantly fewer calories during the first week after the dietary switch, as compared to calories consumed by CH rats. This hypophagia was despite significantly increased plasma ghrelin in KD:CH rats. Finally, KD:CH rats developed hyperphagia over time, and during weeks 6-8 after the diet switch consumed significantly more calories per day than did CH-fed controls and gained more weight than CH-fed controls.
Collectively, these data demonstrate that returning to a carbohydrate-based diet after a period of consuming a ketogenic diet has post-diet effects on caloric intake, body weight gain, and insulin levels.