Move It & Lose It with Prof Trim

How much protein is enough?
The recommended dietary allowance (RDA) of a nutrient is an estimate of the minimum average dietary intake level that meets the nutrient requirements of nearly all (around 97% that is) healthy individuals. Based on this recommendation, the RDA for protein in the diet is 0.8 grams per kg of body weight per day. So a 100 kg (220 pound) man should be eating about 80 g (3 oz) of protein (about the amount in a good piece of steak) per day. Athletes on the other hand are advised to eat up to 3g per kg of body weight per day – around 300 g (11 oz) for a 100 kg man – because of their extra muscular needs.

However, as pointed out in a recent issue of the Journal of the American Medical Association, the term “recommended dietary allowance” is often misleading as it is misinterpreted as being the “optimal” rather than the “minimal” dietary requirement. But protein recommendations for those wanting to lose weight have now been put at around 25% of total energy intake, so for a 10 man needing about 3,500 calories (14,700 kJ) per day, this would translate into a protein content of around 200 g (7 oz)/day, which is obviously more than the RDA, and closer to the athlete level. So who is right?

Because loss of body muscle during an energy restricted diet is counter-productive for good weight loss, the higher level (even up to 35% of intake from protein is more likely to be effective. Are there any risks at this level? Those with kidney problems or potential kidney problems do need to be managed differently, but for the others, there seems to be little risk. As hunter-gatherers, humans often took in as much as 30% of their diet as protein on a regular basis. Hence, it’s likely that we are attuned to a higher protein intake than is current. Of course the other point of concern is that the source of the protein should be lean meats or vegetable proteins. Higher fat varieties (e.g. such as feed-lot farmed animals) are likely to reduce the benefits by increasing the fat (and hence energy) content of the diet.

Dr Garry Egger aka Prof Trim

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