There’s a lot of buzz about a new paper in Nature (yes, I know there’s always buzz about some Nature paper or other), Impact of caloric restriction on health and survival in rhesus monkeys from the NIA study. You’ve probably heard about calorie restriction before. For me the issue I have with it is that people who are very knowledgeable (i.e., researchers who know a great deal abut human physiology, etc.) have given me contradictory assessments of this strategy of life extension. But it’s not totally crazy, there are serious scientists at top-tier universities who practice calorie restriction themselves. This isn’t the final word, but I wouldn’t be surprised if it is going to take decades for it to resolve itself for humans specifically (because some people will always be, and perhaps rightly, extrapolating from short-lived organisms to humans when it comes to modulations of lifespan in the laboratory). The New York Times piece had a really strange coda:
Dr. de Cabo, who says he is overweight, advised people that if they want to try a reduced-calorie diet, they should consult a doctor first. If they can handle such a diet, he said, he believes they would be healthier, ...
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Cell has an interesting piece, profiling four diets, Cell Culture: New Year’s Diets. I know many of the readers of this weblog take an interest in this area. In particular, many subscribe to the Paleo diet or are avid fans of Gary Taubes’ Good Calories, Bad Calories, as well as Art Devany’s ideas. Personally I think one issue which we need to acknowledge more are individual differences. The returns on the margin for a given diet may differ from person to person. The morbidity cost to someone with a family history of type 2 diabetes who has a weakness for dessert is likely much higher than someone without such a family history.
The Cell article gives a scientific overview of the diets in question, and then has pointers to the scientific literature.
- Atkins diet
Inagaki, T., et al. (2007). Cell Metab. 5, 415–425.
Badman, M.K., et al. (2007). Cell Metab. 5, 426–437.
Ma, W., et al. (2007). J. Neurosci. 27, 3618–3625.
- Flat Belly Diet
The Lipid Messenger OEA Links Dietary Fat Intake to Satiety
- Sensa Diet
Small, D.M., et al. (2005). Neuron 47, 593–605.
Ruijschop, R.M., et al. (2009). J. Agric. Food Chem. 57, 9888–9894.
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Happy Thanksgiving Day to all the Americans out there. This is a day to loosen the belt a bit, but after the Holidays you probably want to think about slimming back. So, ScienceDaily, Obesity Riddle Finally ‘Solved’, and, Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance. The upshot seems to be that a high protein-low (refined) carb diet worked best in a large sample of Europeans.
Myself, I was in the 155-165 pound range between 2000 and 2007. 2008-2010 I’ve been in the 140-150 range, and usually closer to the low end than the high. I went from a waist size in the 31-33 inch range to 28-30 range (I wear 28s regularly now). I’m moderately active in that I walk a lot, but I have totally turned away from refined carbs. I am not a religious ‘Paleo’, but I do track glycemic indices and glycemic loads for various foods rather closely. That being said, different people have different biologies. I think that’s important to remember. As a South Asian I have a higher risk for type 2 diabetes, so I’m particularly vigilant about sugar and other variables which increase my probabilities for chronic diseases. If I was a Northern European I might have different priorities, and chill out a little bit about dessert. Life is about trade-offs, and pleasures do often have costs. I am not much of a sweet-tooth, and I’m genetically predisposed to type 2, so my aversion toward sweets is a rather simple calculation. Others may have different outcomes performing the same operations because of different inputs. The answer to a riddle may vary depending on who is asking.
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Russ Roberts recently had a discussion on Econtalk with Arthur de Vany. A lot of it covered baseball and social science, but he also spent a lot of time on “evolutionary fitness” (see the website at the link). I agree with a lot of what he had to say, but felt that some of his assertions about past evolutionary history exhibited too much certitude in the consensus of the field. In particular, when it comes to nutrition I think that evolutionary informed diets may need to take into account individual differences more than they do. I think there’s an unfortunate tendency of many people who find a particular diet which works for them to strongly extrapolate the efficacy of that diet to everyone else to the same extent. Probably limiting strong advice to near relatives would get rid of most of my concerns since families would share many of the same predispositions.
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The ideas of gene-culture coevolution have percolated all the way to the foodie-sphere, over at Epi-Log at Epicurious, The Health Trend of the Future: The Ethnic-Group Diet?:
So, maybe at some point in the future, a visit to the doctor will involve a full genetic workup followed by a prescribed diet tailored to our individual makeup. I might be advised to eat lots of whole grains and dairy products, while someone else might do better on mostly meat and vegetables. This is probably a long way off though—there’s still a lot of science to be filled in.
The “low hanging fruit” like lactose tolerance has been around a long time. Gary Nabhan wrote Why Some Like It Hot: Food, Genes, and Cultural Diversity in 2004. In any case, family background is obviously going to be important, but information from your ethnic background is also probably useful, especially if you have a small family. Ultimately nutrigenomics might advance far enough that we can get personalized recommendations, but if much of the genetic variation is part of the missing heritability than population-level information might be critical for a long time to come. Additionally, population-level information might be relevant as genetic variations which we know about may expression differently conditional on genetic background.
But a consideration that’s not totally trivial is that diets can change very fast. The Columbian Exchange resulted in the introduction of chili peppers to much of Asia, to the point where the extent of their usage in the local cuisine can be diagnostic as to regional origin. And of course potatoes are a relatively new staple in much of Europe. Though in both of these cases the basic nutritional value or culinary role simply substitutes for what was already on hand, starch in the case of the potato and spice in the case of chili pepper.
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