Very interesting talk on caloric restriction in rhesus monkeys at the UAB Nutrition Obesity Research Center yesterday from Dr. Rozalyn Anderson, Ph.D. an Assistant Professor, at the University of Wisconsin-Madison.
I am super busy at the moment, I am not going to whinge, but I’m in those very exciting last 2 weeks of a grant submission, while trying to get at least one faculty job application off my desk per week, and maintain my papers submission (i.e. not piss off the co-workers whom will write my letters of reference). I refer you to Stella for a nicely scholarly and full discussion of the lecture. I’ll just give you a precis of my take home messages, focusing on the more surprising findings:
When rhesus monkeys were on 25% caloric restriction (without malnutriton) from their ad libitum weight maintenance diet:
*Death from all cause mortality was signficiantly reduced, after a period of ~10 years
*Death from age-related mortality was even more significantly reduced across the whole lifespan
*Almost all forms of senescence were significantly delayed. Interestingly Dr. Anderson really delved into depth here, showing for example how muscle fibres did not show age-related changes
*Fat mass was significantly reduced
*Despite caloric restriction: lean body mass did not decline
*Organ size did decline, but only as expected for a smaller animal
*Despite caloric restriction: basal metabolic rate did not drop. The CR monkeys only saw a drop in the amount of energy used to perform activities, i.e. they became more efficient
*The CR monkeys looked amazing to the naked eye. Their fur remained thick, and so luscious – I was amazed. They made the non-CR monkeys look like they had been rescued from a situation of neglect.
I was very interested in the discussion afterwards. Two points, specifically:
*Dr Anderson was asked whether the macronutrient that was restricted (fat / carb / protein) made a difference. She said that in the absence of malnutrition, and excluding some disease-specific effects, no. Her informal observations was if you were either ~25% under, or 25% over your caloric needs, it didn’t matter much what you ate. If you were under: your body would adapt and use everything. If you were over: you were going to cause yourself trouble whatever you were overeating. My personal experience with the latter backs this up (overeating protein as a ‘free’ food). It is just if you are somewhere in the middle; eating around your caloric needs, that macronutrient balance might make a difference.
I wonder if this could partially explain why some people can eat fast food endlessly, and remain metabolically well? These tend to be slimmer people, so I could guess they were eating less than their caloric needs: at this point, it doesn’t matter what they are eating. Then take individuals who eat around their caloric needs from junk food, and are suffering metabolic dysfunction: is it because they are in the ‘somewhere in between’ zone where what you eat matters? If you are going to always eat poorer quality food or fast food, do you need to calorically restrict to remain healthy? I don’t know – pure anecdotal speculation (it’s my blog. I’m allowed 🙂 )
*She didn’t recommend this for humans. Stella touches on this: she says the psychological harm from restricting herself outweighs any physical benefit. This was Dr. Anderson’s point: do you want to take away a glass of wine after a hard day? Something yummy to eat to look forward to? I don’t agree with these views. I think we have come so far from what is good for us, in terms of exercise and eating, that drastic measures are needed. My example: I need ~19000 calories to ‘maintain’ , given my lean body mass (I lift), and general activity level (possibly slightly more since I have been regularly practising HIIT, but let us be conservative). Throw in my daily activity, and I burn, on average, 2,200 calories a day. I currently eat 1,300 a day. It sounds small, but I eat a large breakfast (oatmeal), a filling snack (Banana and PB or Larabar, sometimes apple and nutella.. mmmmm….), lunch (carbs, protein, veg, sometimes fruit), snack (fruit + nuts or veg and hummus) and dinner (protein, lots of veg, salad and a good whollop of MUFA e.g. 1/2 an avocado). I have energy for all my workouts (when I am not suffering allergies, but that doesn’t count 😉 ). I am clearly building muscle. I am rarely hungry. It’s easy. I only exercise 20 mins – 1 hour 5 times a week. And I am on a 40% restriction. I can add in some wine, or a beer (I don’t like beer), or I can ‘eat out’ (with appropriate portion sizes), or I could have some cake or chocolate ontop of all this… and still be on 25% restriction or less. It is not that hard for me. I am not sure when we started touting that this sort of behaviour was so wildly out of the norm, or so crazy, or so hard to follow. And I am not sure that helps people who feel they want to follow a different dietary lifestyle, but find it daunting.
Just a thought. Just a thought from someone who recently put on 25 lbs 🙂 Take it with a pinch of salt and do respond honestly, but please don’t flame me 🙂
The seminar is likely to be posted here soon.