It’s one thing to lose weight, it’s another to keep it off. Most of us will be familiar with the concept that the great majority of people who lose weight regain it over time. And the results of a recent study suggest that as the body loses and weight, the body risks undergoing gradual degeneration in terms of its composition.
When individuals lose a reasonable amount of weight, the majority of the weight they lose is usually in the form of fat. But weight loss can be contributed by other things too, notably muscle. Generally speaking, about one sixth to one quarter of weight loss is actually ‘lean’ mass (mainly muscle).
The American Journal of Clinical Nutrition recently published a study in which followed up post-menopausal women after they had spent 5 months losing weight on a calorie-controlled diet, with or without aerobic exercise [1]. The average weight loss was about 11.5 kg during this time (exercise, by the way, did not improve weight loss over dietary change).
This follow-up found that the average overall weight loss a year after the weight loss intervention stopped was still about 8 kg. Of course, some women did better than others, with some maintaining their weight loss well and others regaining a significant proportion of lost weight.
The interesting thing about this study is that the authors monitored not only weight, but the body composition. This allowed to calculated the relative amounts of fat and muscle lose and regain by the women. Here, in summary was what they found:
For each 1 kg of fat lost during the weight loss phase, women lost an average of 0.32 in lean body mass.
For each 1 kg of fat regained subsequently, women regain only an average of 0.08 kg of lean mass.
Putting this in percentage terms, 76 per cent of weight lost originally came in the form of fat.
When weight was regained, about 93 per cent of this was fat.
The problem here is not just that the body is getting proportionally fatter. The loss of muscle is a concern too, as muscle mass has some bearing on metabolic rate, and it also can determine functionality. It’s not good to lose muscle, particularly as we age, as it can leave us weak, frail, incapacitated and prone to falls and injury.
One thing that may help preserve muscle loss is to put some emphasis on protein in the diet. There was a recent study published which found that in older women losing weight, supplementing them with whey protein powder (25 g X 2) led to more favourable fat:lean ratio in lost weight compared to the same dosage of carbohydrate (maltodextrin) [2]. This was associated with improved physical functioning in the women too. And the women supplementing with protein lost about twice as much weight too.
I’m not aware of any research in the area, but emphasis on protein is likely to help should there be any weight regain too.
Of course, one other approach would be to maintain or possibly even build muscle mass during and after weight loss with a little regular resistance exercise.
References:
1. Beavers KM, et al. Is lost lean mass from intentional weight loss recovered during weight regain in postmenopausal women? Am J Clin Nutr. 2011 Jul 27. [Epub ahead of print]
2. Mojtahedi MC, et al. The Effects of a Higher Protein Intake During Energy Restriction on Changes in Body Composition and Physical Function in Older Women. J Gerontol A Biol Sci Med Sci. 2011 Jul 27. [Epub ahead of print]
