For weight loss, carbs in or out?

Anyone who has lost significant weight by design will happily tell you how it was done and what they believe is the perfect diet for successful weight loss. It will always be a low calorie diet, no matter how they dress it up, although the composition of that diet is the stuff of discussion and argument.

Weight loss significant

An Australian study put 141 overweight subjects on a low kilojoule meal replacement diet (eg milkshake) for three months providing 210 kJ (500 Cals) a day. That then followed with 12 months of either a high protein or a high carbohydrate individually tailored diet. So, everyone was followed for a total of 15 months. Each diet provided the same amount of kilojoules/calories. Both groups lost an average of 16.5 kg (36 lb) in the first three months and maintained a weight loss of 14.5 kg (32 lb) twelve months later.

Heart benefits

The high protein diet provided about twice the protein of most free-living westerners, so being a low energy diet, it still meant modest servings of meat and fish. The high carb diet was closer to what most people eat when “watching their weight” (it wasn’t really high in carbs). It wasn’t just weight that changed. Bad cholesterol came down, good cholesterol went up and triglycerides came down. Blood pressure remained pretty much the same.

Calorie amnesia

The study also revealed a common phenomenon, that of under-reporting. It has been well documented that people frequently get “calorie amnesia” and forget to report exactly what they have eaten. Published data on under-reporting shows we forget 12-54% of what we eat, making it difficult to identify why weight creeps on because all you remember is the salad and fruit you eat. In this study the ladies under-reported by about one-third.

Surprisingly, the guys had much better recall with an accuracy of 99%. I say, surprisingly because under-reporting of 1% is the lowest recorded. I’m too frightened to make a gender related comment here, but you can bet that had this study been about beer, that 1% figure would have been different.

What does it all mean?

Success is only ever likely if you follow a style of eating that you are going to enjoy for the rest of your life. That might be with bread or without it. Over time, both groups began to eat more and more similarly to each other, which may partly explain why the researchers didn’t see any difference in weight loss between the two diet groups.

Those that are involved in research like this are selected because they are more motivated than the average. They also got free monthly counseling, which is not within every person’s budget. Even so, 40% of those in the study dropped out before the end of the 15 months. As you have heard me say before, losing weight is quite easy. So is gaining weight. Maintaining the weight loss is the really tough part, way beyond what most people can cope with. This study showed that it’s possible to maintain weight loss over 12 months – the type of diet didn’t make any difference.

Reference: American Journal of Clinical Nutrition 2009; 90: 1203-1214