There is this new thing, called the protein leverage hypothesis, that is being studied as a possible contributor to our obesity epidemic. Protein leverage is the innate drive to eat more if you are not getting enough protein. Your body needs protein to grow and repair. So if the diet is lacking in good protein, that is a complete protein with all the essential amino acids that are the building blocks of protein, then you are driven to keep eating.
The inventors of the terms “protein leverage” (PL) and the “protein leverage hypothesis” (PLH) in 2005 have reviewed these ideas in this month’s issue of the journal Obesity (2) and explored some of the implications of this thing as a possible cause of obesity.
The most common example and understanding of this sort of thing is the folklore about how pregnant women want to eat strange things, even dirt, in order to get certain vitamins and minerals that they must be lacking in order to feed the cookie monster in their uterus. It has been shown that all kinds of animals have a drive to keep eating whatever is available to them in order to get enough protein. Part and parcel of this idea is that they may wind up over eating certain things and that they will need to get rid of the excess of stuff they don’t need. But there are many examples of nutrient excesses that they don’t handle well and that can likewise be toxic for animals. So we have multiple nutrition-specific appetites that must be calibrated.
This is complicated but it can be shown that free living humans eat more calories when they eat less protein. From 1961 through 2013 as we were experiencing the obesity epidemic we were eating more calories but about the same amount of protein. Since we need only very little dietary protein if we are not growing or pregnant or recuperating from surgery and accidents that would seem to mean that this protein leverage hypothesis is wrong as an explanation of the obesity epidemic. But as a percentage of total intake, protein consumption went down, contributing to the support for the PLH. But if you do more math it can’t explain all of the average increase in obesity.
Another analysis using differential equations(3) and further commentary(4) in this month’s edition of Obesity and further commentary(5) elsewhere add to the discussion. The bottom line is that changing the percentage of protein in the diet has not made any important difference in the trajectory of ever increasing weight gain despite lots of commercial efforts to sell high protein everything.
This may be a thing but it might not even really be a thing.
2. Raubenheimer D, Simpson SJ. Protein Leverage: Theoretical Foundations and Ten Points of Clarification. Obesity. 2019;27(8):1225-38.
3. Hall K D. The Potential Role of Protein Leverage in the US Obesity Epidemic Obesity 2019;27(8):1222-4.
4. Hill CM, Morrison CD. The Protein Leverage Hypothesis: A 2019 Update for Obesity Obesity. 2019;27(8):1221.
John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- [email protected] or phone (740) 354-6605.