Diet Alone, Exercise Alone, Or Both For Fatloss?

14 Mar 2010 19:51

By Eric Troy

The age old question. And it seems to spark absolute outrage on all sides. Which is "better" for fatloss? Diet alone, exercise alone, or a combination of diet and exercise intervention?

Most people involved with helping the very overweight or obese lose weight will tell you that if you have to choose one then diet alone is the way to go.

The exercise industry seems to get downright incensed when this is mentioned. A fairly recent Time Magazine article discussing this sparked some pretty pissed off reaction among fitness experts.

Well, all these things are but tools. And when the experts get precious about their tools rather than the results garnered from judicious use of those tools, we have a problem. Frankly, if someone wants to really help another person it shouldn't matter to them that their favorite chisel isn't the 'best' single tool for the job even though it was the first tool they ever bought and they have more fun using it…and look more authoritative with it in their hand.

As I've said time and time again in this blog and others, you will not work off a bad diet with exercise. For fatloss, diet IS the first thing to consider. You must get your food habits under control. When I say diet, of course, I do not mean "dieting" necessarily. I mean your overall eating lifestyle, from here on out.

Now, people will tell you that exercise has many benefits. Strength training especially! So true, so true. But let's not count our fat cells before they are hatched.

A recent meta analyses out of Germany yet again confirmed what I already believed. Diet alone trumps exercise for weight loss but diet and exercise combined has the greatest effect.

This analysis started with a very broad search that resulted in over 36,869 papers of which an initial 337 met the criteria. These 337 papers were culled down to thirteen. Each set of reviews were performed by independent researchers. This should serve as a good illustration of just how difficult and painstaking this type of research is and just why you shouldn't listen when someone cites one randomized controlled trial to you. Not to mention the other ones. The abstract follows.

Bettina Schaar1, Corinna Moos-Thiele2 and Petra Platen3

The objective of the following meta-analysis was to determine what kind of treatment, or combination of treatments, has the greatest effect on weight loss in overweight and obese adults.

A systematic search was conducted of the available literature published between 1993 and 2006 that covered randomized controlled trials on overweight and obese subjects who underwent treatment consisting of physical exercise and/ or changes in diet. The scope of the search thus incorporated seven relevant databases.

Using 6,545 key word combinations, the electronic search yielded a total of 36,869 abstracts. 13 relevant studies with a total of 826 subjects (BMI > 25; 17 - 68 years of age) met the meta-analysis criteria. The courses of treatment included “diet (d)”, “physical exercise (pe)”, “diet and physical exercise (dpe)”, and “no intervention (ni)”. The results confirmed the hypothesis that the combined intervention “dpe” had the greatest effect with regard to weight loss. The single treatments “pe” and “d” also led to weight loss, with “d” having a significantly greater effect than “pe”.

The main reason for the small sample size of thirteen studies out of 36,819 was that the experimental design and/or procedures of most studies were inadequate. A common error was a failure to assign subjects randomly to the different treatment groups. The results of our meta-analysis indicate that a combination of diet and physical exercise is the best form of treatment to induce weight loss in overweight individuals in the first weeks, followed by physical exercise to maintain weight loss.

Furthermore, the authors found that out of one hundred individuals the probability that diet alone would result in weight loss was forty percent greater than no intervention. Well, it should be obvious that doing something about your diet would have a greater chance of causing weight loss than doing nothing. Although, to be clear, the data does not, and could not, say anything of just what the various dietary interventions were. But they found that out of 100 people the probability that exercise alone would induce weight loss was only eight percent greater. Now, I'll bet that wasn't obvious. Again, the combination of diet and exercise had the best results in weight loss and in increasing lean body mass (of great importance for a healthful outcome).

The authors mention the previous reviews such as the meta-analysis by Garrow and Summerbell in 1995 which also found that a diet and exercise combo had the greatest effect. That review, gulp, found that "strength training" alone had no discernible effect on weight loss. The quotations around strength training were the authors but I would have used one as well since it would be difficult to pin down just what strength training WAS in such a review. But I get tired of always being right in the long run like when I said that strength training is not the key to weight loss…how am I ever going to learn anything if I always end up being right the first time? No, I don't read fatloss meta-analyses in my spare time.

Sorry, strength training is just not "the key" to fat loss and the next time someone tells you that or you read that, do me a favor, tell them to come on over here and explain to me just how that is so. It's just not. If you tell me, Eric, I want you to get me really strong but I want to stay fat, I'd say "No problem!". I mean, I would have a problem with it but it would be fairly easy to do. I couldn't promise you that you would preserve every fat cell you have now but I could get you lifting very heavy things while still having a nice padding of fat when you're done. That would be easy to do. And, if we followed some of what passes for strength training diet advice these days, you could just pick a huge amount of calories, stuff your face, and get strong AND fat and bloated. Minimal charge.

I suppose it depends on what you think strength training is but if you think you absolutely have to shed the gut to deadlift 400 to 500 pounds, you'd be wrong. You may be able to be more efficient and make better strides for various reasons if you shed the excess fat but it is not a prerequisite for absolute strength gains. And when I say strength I usually mean changes in absolute strength (or really the strength deficit for S&P fans). Yes, I know that Olympic weightlifters are "the strongest people in the world". Let's not debate that again. This may shatter some of those dreams of building your deadlift and squat and automatically looking like a bodybuilder. Sorry to rain on that parade.

I mentioned EPOC in that post I linked above. EPOC stands for Excess Post Exercise Oxygen Consumption. In that post I said that EPOC was easily overestimated and over-indulged by fat loss experts who (insert nasty stuff here).

Right again? Man, am I tooting my own horn in this post but it is fun being right all the time. In a recent study published in the International Journal of Sport Nutrition and Exercise Metabolism: Post exercise Fat Oxidation: Effect of Exercise Duration, Intensity, and Modality it was concluded that "although post exercise energy consumption and fat oxidation can be augmented by increasing exercise intensity, these these benefits cannot be exploited by undertaking interval exercise (1:2-min work:recovery ratio) when total energy expenditure, duration, and mean intensity remain unchanged." Thanks to Jamie Hale for giving me a heads up on that study. I can't share the entire study with you since it is not open access. Sorry.

To put it in a nutshell, 10 to 20 minutes of HIIT does not make up for 23 and a half hours of sitting around. Although interval training and any training that uses such a combination of high intensities with low intensity cool down periods are still a very valuable mode of exercise when it comes to conditioning parameters, for fat oxidation/energy expenditure alone, the effect of the exercise bout itself is more important than the post exercise effect, which is trivial when compared to total energy consumed during exercise (according to the study). In other words, EPOC is not your miracle ticket to "free fatloss".

The old mantra "Move more, eat less" still holds true. You need to consume less energy and burn more OVERALL. I still find that a tired bit of over-simplistic sloganizing since the relationship with food and exercise is a complex one that can't be solved by a trite little mantra. But the heart of it reflects the larger reality of fatloss.

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This page created 14 Mar 2010 19:51
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