In my final interview, I've decided to throw some commonly-asked questions at Lyle--questions which are forever appearing on the Internet. I figured this would make for an interesting, informative piece, and perhaps put to rest some of the debates that frequent the various message forums... or add more fuel to the fire. I'm sure you'll find that this read will equip you with new insights on some controversial topics.

For the final interview I‘ve decided to throw some commonly-asked questions at Lyle--questions which are forever appearing on the Internet and in print. I figured this would make for an interesting, informative piece, and perhaps put to rest some of the debates out there… or add more fuel to the fire. I'm sure you'll find that this read will equip you with new insights on some controversial topics.

Maki R: For some time now, doctors, trainers and coaches have had an ongoing problem with people who complain of weight-gain even though they’ve been exercising vigorously. The standard diagnosis in fitness circles says that a diet lacking in calories is the culprit. In most cases, many are told that it's because their body’s metabolism is cruising along at a snail’s pace. The body, in fact, has been storing the food as fat instead of distributing it as needed. Is there any truth to this?

Lyle M: Over the years, there's been a long held debate over the fact that people swear that they can gain weight (or not lose weight) on low calories. There's typically been two interpretations of the data: either there are people out there who's metabolism are just so far outside of the norm that they violate basic laws of thermodynamics OR that people are just really shitty at estimating how much food that they eat and how much exercise they do.

Maki R: I think that the majority of the exercising population fails to pay attention to certain areas such as portion control which, in turn, takes them several steps backward instead of forward.

Lyle M: A number of recent studies support the latter conclusion. The fundamental problem with most of these reports is that they are self-reported. That is, you ask
people how much they are exercising and they say "A ton, at high intensities" and then you ask how much they are eating and they say "Oh, almost nothing." Then you actually track them covertly and you find that most people are vastly over-estimating how much exercise they are doing, and vastly under-estimating how many calories, they are burning. These mis-estimations can vary by 50% either way (that is people may over-estimate their activity by 50% and under-estimate their caloric expenditure by 50%). In addition, I want to make it clear: I'm not saying that these people are doing it deliberately, or lying. Most people are simply very bad at this sort of thing.

Now, that said, don't misunderstand me: there are most certainly adaptive decreases in metabolism with dieting that do occur. This, of course, reduces maintenance calorie needs. Now, part of the reduction simply has to do with the weight loss itself. Both resting metabolic rate and the calorie burn during activity (moving around and exercise) are related to bodyweight; so less weight means fewer calories burned (if you don't believe me, put a 10 lb weight in a backpack and carry it around all day, tell me how much more tired you are from the extra workload). Carrying around 100 lbs of fat burns a lot of calories.

Maki R: No thanks; I have enough trouble carrying around my stomach as it is.

Lyle M: But there is also an adaptive component that is a drop in metabolic rate beyond what can be explained by the drop in bodyweight. This gets back to the leptin system I talked about earlier: the body down regulates total metabolism during dieting to compensate and dropping leptin appears to be the main signal involved.

Now, during extreme dieting, either extended periods to very low body fat percentages, or simply very low calorie dieting, this adaptation tends to be the greatest. In one of the classic studies (the Minnesota Semi-starvation study), lean men were put on 50% of maintenance calories for 24 weeks. They pretty much lost all of their body fat and had a reduction in total energy expenditure of 36%, of which 16% was part of the adaptive response. However, their maintenance calorie requirement never went below their caloric intake. Now, that's a very extreme reduction, 5-10% is closer to average. That is, the adaptation to low calorie dieting, even extremely low calorie dieting is NEVER large enough to suddenly bring that person back into positive energy balance. You see a 5-10% reduction in resting metabolic rate at the maximum.

So say you have someone with a total energy expenditure of 2000 calories/day. Now you put them on 800 cal/day. Let's assume the same level of adaptation as seen in the Minnesota study (which is the largest value I've ever seen): 36%. So, after a while, their energy expenditure is down 36%. That's 720 calories, giving them a new maintenance level of 1280. Fine, yes, that will certainly slow weight loss, but they are still in a caloric deficit. They don't magically start getting fat again *unless* they start overeating.

Maki R: And, sad as it is, most will start over-eating again.

Lyle M: Basically, I've seen no evidence in the studies (done over 3 decades where food and activity are rigorously controlled, and that's the key) that daily maintenance calories can ever somehow drop below caloric intake during low calorie dieting. Yes, it will adapt and I've seen it literally stop fat loss in its tracks. And certainly, if you jack up calories rapidly under those conditions (a depressed metabolic rate), you're going to get rapid fat gain. However gaining fat on super low calories has more to do with people being terrible at estimating their caloric intake and expenditure.

Ultimately, it comes down to the following discrepancy: in controlled lab studies where caloric intake and expenditure are rigorously controlled and measure (and I'm talking they spray these folk's plates with water and make them drink the mush so they know *exactly* how many calories they are eating), the observation of someone gaining weight on super low calories has NEVER been observed. That's over decades of study and lord knows how many subjects. Then we have these self-reports of folks gaining weight while dieting, coupled with more studies showing that people usually underestimate food intake and over-estimate activity.

I hate to be a party pooper but people are deluding themselves.

Maki R: Well I'm sure you've been asked this question many times, but since it's always being debated I have to ask you. There's a nasty myth in circulation right now claiming that only 30 grams can be taken in. How much protein can the body assimilate at one time?

Lyle M: Well, I think part of the problem has to do with what you mean by 'assimilate'. That is, you sometimes see the '30 grams per meal' (or whatever it is) to mean how much the body can digest, utilize, or what have you. But nobody seems to really want to nail down what they are talking about.

Maki R: Ok, let me rephrase the question: "how much protein can the body handle in one sitting?"

Lyle M: I consider all of this "The body can only use X grams per Y" as a lot of nonsense. First and foremost, it makes no evolutionary sense (how I've been looking at a lot of physiological processes lately). That is, our ancestors did not eat protein in small amounts throughout the day. Yet, anthropological studies show that they had more muscle and bone mass than most of us. Rather, they were more likely to eat a ton of protein after a kill, and whatever amount they got from vegetables and such the rest of the time. Massive protein intakes at once were more likely the norm during 99% of our evolution than not. This means that our guts evolved to handle it. In addition, when you start looking at digestion and such, you see exactly that: even with massive protein loads (I vaguely recall they've looked at like 1.5 g/kg of beef all at once), digestion still stays very high (on average 90-95% for animal proteins meaning you're losing at most 10 grams of protein/100 grams ingested). The body can digest/absorb pretty much anything you throw at it. You won’t be pooping protein if you eat 35 grams at a sitting, is what I'm saying.