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Interesting article on protein, obesity, and ageing

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I read a very interesting article about protein intake in New Scientist recently:


It presents a theory that we have multiple hunger drives for different nutrients (protein, carbs, fat, sodium and calcium), but that the protein drive dominates.

The main point of interest is here that the body/brain stops you eating too much protein, because it accelerates ageing.


when locusts have a wide choice of foods, their two appetites collaborate so they consume an optimal diet. But when they are given imbalanced foods, as in our first experiment, the appetites for protein and carbohydrate compete, and protein wins. That suggested that, more so than carbohydrate, protein has to be carefully calibrated in the diet. We were later to learn why. If an animal has too little, it can’t grow and reproduce, and too much protein speeds up ageing.

(In a related book, they argue that its the low protein in the Okinawan's diet, combined with high levels of fibre to limit the effect of "protein leverage" [which would otherwise cause overeating], that is responsible for their longevity, rather than calorie restriction per se.)

Also of interest are the implications for the obesity crisis.


One of our students had access to an isolated chalet in the Swiss Alps, far from shops or restaurants. She recruited a group of 10 friends and family and took them there to spend a week as human locusts.

For the first two days, participants chose whatever they wanted to eat from a highly varied buffet. Everything they ate was weighed, and their intake of calories, protein, carbs and fat was recorded (caffeine, alcohol and chocolate weren’t available).

On days three and four, the volunteers were divided into two groups. One group got a high-protein buffet, the other a low-protein, high-carb and high-fat buffet. For the final two days, they returned to the original diet.

In phase 1 of the experiment, our human locusts reliably got about 18 per cent of their calories from protein, in keeping with studies that show people typically need 15 to 20 per cent.

In phase 2, everyone maintained their absolute protein intake. But to do so, those on the low-protein diet had to eat 35 per cent more total calories, while those assigned the high-protein diet ate 38 per cent fewer calories. Our volunteers responded like locusts, with their appetite for protein dominating, and determining the total consumption of food.


As a result of our discoveries on the ways in which nutrient appetites interact – the dance of the appetites, as it were – we were confident in putting forward another hypothesis: in a food environment that is protein-poor but energy-rich, people will overeat carbs and fats as they strive to reach their protein target.

If true, the implications would be huge. It may come as a surprise, but we do actually live in a protein-dilute, energy-rich food environment. According to the UN’s Food and Agriculture Organization, between 1961 and 2000, the proportion of protein in the average US diet fell from 14 per cent to 12.5 per cent, with the balance made up of fats and carbs. Given that shift, the only way people in the US could have maintained their target protein consumption was to increase total calorie intake by 13 per cent – more than enough to create an obesity epidemic.

Intriguingly, in our experiments with people, we found that most of the extra calories eaten by those on a low-protein diet came from savoury snacks, especially those that tasted of umami, the signature flavour of protein. Protein-deprived subjects were craving things that tasted like protein, even though they were made of carbs. Our food environment is awash with such umami-flavoured carbs and fats, which we call “protein decoys”: crisps, instant noodles, crackers and so on.


Edited by elatedsquirrel
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  • 2 weeks later...

It doesn't tell you what kind of protein (animal or plant) or what kind of carbs (potato chips, or whole grains and fruots and veggies).

There are major differences among sources.

The much studied original Okinawa diet is9% of mostly plant protein and minimal fat, with very high carbs intake, much of it from purple yams.  Definitely no obesity there until the 1970s, when animal protein and fat intake dramatically increased, together with their income.  My guess is, Frito Lays taste better to most people than purple yams :)

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