IDM (Intensive Dietary Management) Program is a program developed by a Canadian doctor for combating obesity & (I think?) managing diabetes. I started reading one of his blog entries from a google search for fasting and exercising together, and found myself in the middle of his fasting series. It was talking about how our muscles can be made to burn fat more efficiently via exercising while fasted, after an initial adjustment period of a few weeks. I was interested and went back and started at the beginning with the calorie series. There are a bunch of blog entries starting here: How Do We Gain Weight? There is also a 6 hour video lecture series for those preferring a lecture format. Part one is here: So far I've read the calories series, exercise series, and am on part 17 of the hormonal obesity series. Overall impression: Manipulative language is pervasive throughout, but if you can dig through it there are some interesting conclusions. I disagree with some of his conclusions (not that they are wrong per se, but that there isn't evidence to support them), but others I did find convincing. He does reference a lot of studies. I don't know that I'll review/summarize more of it, aside from maybe the fasting series when I get there. General summary of his message/conclusions so far (calorie, exercise, hormonal obesity series through #17). Some of this was news to me, some wasn't: - Your body weight is more like a thermostat than a scale; if you decrease calorie intake, your body reduces energy expenditure to match, same if you increase calorie intake. (All of this while holding macronutrient composition stable. Referenced studies were done with liquid nutrients in a fixed macro ratio.) - Increased exercise is generally compensated for by lower energy expenditure during non-exercise times and/or greater calorie intake. - Eating fewer calories (holding macros stable) and exercising more ((discounting crazy high levels of activity, I imagine; the referenced studies involved regular, lower intensity exercise)) will not result in other than trivial weight loss. - The main hormonal drivers of obesity are insulin & (to a lesser extent) cortisol. - Insulin tells the body to go into storage mode: turn glucose into glycogen to store in the liver, turn on the synthesis of fats in the liver. Low insulin levels do the opposite, turning glycogen back into glucose & disassembling fats. Insulin levels & insulin resistance (which increases your insulin levels) are the main driver of your bodies weight thermostat. - Eating many times a day vs fewer times a day: he says many times (6 meals in a 16 hour period, for instance) is worse than few times (e.g., 3 meals in a 12 hour period, 12 hour fast) for you as it sustains insulin, which is released in the presence of food. ((While an interesting hypothesis, he didn't back this up with sufficient evidence to convince me. No references to studies for statistical data about this, unlike most of his other conclusions.)) - Insulin resistance grows with time spent obese. The longer you spend obese, the harder it is to undo, because you get higher and higher insulin resistance over time as you spend more time obese. - Fiber is an anti-nutrient; it reduces the absorption of certain nutrients. He says that nature provides foods that are high in carbohydrates (which spike insulin & glucose levels) with higher amounts of fiber (which smooth out spikes in insulin & glucose levels). And that nature has no reason to provide fiber with dietary protein & fat because they do not cause the same spike in insulin & glucose levels. ((My thought on this is his explanation is backwards: our digestive system evolved in the presence of nutrients such that carbs were almost always packaged with fiber, so it came to rely on that for healthy bodily function.)) - Processing is bad. Processed carbs are worse for you than the less processed ones because the fiber & natural fat are removed. Low fat diet (recommended in 1977 by the US government) led to increased carb consumption, and the USA was eating a lot of processed carbs to replace fat in the diet. This is when obesity started increasing rapidly.
Ok I read some more (over 40 posts on hormonal obesity, around 25 posts on fasting, and a bunch on some other stuff about things like mTOR/autophagy). Revisiting restricted eating times: He did post more about this with referenced studies. Restricting eating to a shorter time frame (8 am - 2 pm, for instance, vs 8 am - 8 pm), without altering calories or content of food (i.e., eating the exact same thing in both groups), does result in fat loss compared to eating over a longer period of time. His main points (in general supported with referenced studies): - Intermittently fast when you can (e.g., try to get at least 12 hours of fasting a day, say between dinner & breakfast. If you can get 16, great. If you can get 20, great.) This will lower the amount of time insulin is in higher concentration in your system. - You can fast for long periods of time (weeks or even months) without break so long as your BMI/body fat is sufficient to support it, but (very) strongly recommended to be monitored by a physician if doing so. He says STOP immediately if you feel unwell; hunger, irritability, and constipation are ok, any feelings of dizziness/weakness/etc are not normal and indicate you should stop immediately and consult a physician. - You won't lose lean mass fasting--fasting increases HGH by a lot (300% in 5 days fasting, up to 1250% increase observed in longer fasts such as 30+ days), especially once ketosis starts. Studies show that lean mass is not lost. Exercise will help maintain lean mass during fasting. (One guy did a 44 day fast just sitting in a glass box; his muscle atrophied, but all of the atrophy was from inactivity.) People remaining physically active apparently don't lose lean mass. - BCAAs taken during fasting will spike mTOR, which will reduce autophagy. May be relevant depending on your goals. (Autophagy cleans out damaged proteins.) May increase insulin a bit too (protein does, not sure if individual amino acids do on their own, he may have discussed this but if so I don't remember what he said about it). - If your body wants to use protein/essential amino acids, it will recycle them from proteins dismantled by autophagy. - Blood glucose & electrolyte levels remained stable within normal ranges (though blood glucose at least fell some, it was still in normal range) over longer fasts. - Electrolytes are probably good to take with intense exercise if fasting for a long period of time... but in general are not needed while fasting. Even with 60 days of fasting, potassium levels fall though not below recommended levels, magnesium calcium and phosphorus levels remain the same. If concerned it isn't harmful to take a multivitamin while fasting. (It may make your stomach a bit unhappy.) - TDEE actually goes up while fasting (by ~10%), unlike under calorie restriction (where TDEE will fall to match reduced intake). - There is an adjustment period during which your energy, your muscle strength and overall capacity will go down, but they will recover usually after about 2 weeks (even if you continue fasting), can take up to 4 weeks. My takeaways: - I can fast for a week or two at a time if I want, and still exercise. I may try this at some point. - If I want to adjust my muscles to burning fat so I can train without issues while fasting, I could do shorter (than the 2-4 weeks it takes to adjust) fasts (say, 48-60 hours) and exercise fasted on my own pace; after several (or more) of those I should be able to do a longer fast and still train, even intense stuff like Muay Thai. I am going to play around with longer fasts. I'll write about it in my training log when I get around to it.
