Monday, 5 October 2009

Exercise WILL Make you Thin - if You Really Want it to

For years we thought you needed to exercise to lose weight. Don’t exercise, you get fat. Exercise, you get thin. Simple.

Then we realised this advice may be wrong. Studies showed that exercise increased the appetite, so people ate more. Books like Good Calories Bad Calories dismantled the calories-in-calories-out hypothesis. Respected commentators stated that getting the diet right is by far the most significant contributor to weight loss.

Recently, an article appeared in Time magazine article, Why Exercise Won't Make You Thin. It was widely commented on in the health and fitness blogging community and touted as evidence that the mainstream might finally be 'getting it.'

Yet, one such commenter, Rusty Moore on Fitness Black Book posted an analysis of the article which contained a single, important phrase, challenging this new doctrine:

The biggest flaw in the article is his notion that exercise gives you no choice but to over-eat.


Key questions of health and fitness almost always get polarised. People want simple – and the there are those who exploit that for their own gain. The subtleties are brushed aside in an orgy of gourd following a lá Life of Brian.

Two subtleties that do discussed in health and fitness circles are:
  • Intense, interval-based training may be more likely to create the conditions for weight loss without self-defeatingly stimulating appetite.
  • The effect on appetite of exercise may vary according to the type of food eaten and the metabolic state of the subject (i.e. are they adjusted to a low carbohydrate diet or riding the high carbohydrate merry-go-round.)
Rarely is psychological state discussed in any depth. How badly does a person want to lose weight? How strong is their will power and self discipline? The research appears to treat people as machines. Get hungry, eat food.

I believe that if someone really wants to lose weight with exercise, then they will, regardless of the type of exercise they are doing or food they are eating.

I will admit up front that I am far too lazy to delve into the full detail of all the studies on exercise and weight loss - scientific papers make my eyes bleed; but I did look at the methodology section of a study referenced by the Time article. This is what it said about how the subjects were recruited:
… 464 postmenopausal women within the age range of 45 to 75 years, who were sedentary (not exercising more than 20 minutes on 3 or more day a week, and [less than]8000 steps per day assessed over the course of one week), overweight or obese (BMI 25.0 to 43.0 kg/m2), and had a systolic blood pressure of 120.0 to 159.9 mm Hg were randomized to 1 of 3 exercise groups…
Notice that the criteria here are mostly physiological. Machines. Get hungry, eat food.

Two things I would have wanted to know about the subjects:
  1. What was their attitude to weight loss? Did they want to lose weight? We cannot assume that just because they were overweight or obese that they wanted to lose weight.
  2. How strong was their willpower?
I am not pretending that either of these is easy to measure – but equally I think we can assume that the psychometric testing industry has successfully tackled them at some point.

The attitude to weight loss is especially important. The implicit point of studies like this is to evaluate how effective exercise is as a weight loss tool… a tool which one assumes would mainly be used by people who want to lose weight. So there’s not much point studying people who don’t want to lose weight, right?

I have not examined the results section of the study. For the sake of my eyes, I did not delve beyond the methodology; but what we can assume is that the average weight loss for the exercise group was no greater than the average weight loss for the non-exercise group.

Yet by the laws of natural variation there must have been exercisers who did lose more weight than the average non-exerciser.

In other words, for whatever reason, at least some people must have lost more weight through exercise. Why?

In my experiment, the subjects would be tested for attitude and personality characteristics:
  • Do they want to lose weight? How badly?
  • How much will power and self-discipline do they have?
We would then look for a link between these factors and weight loss. If there is a link, is it more pronounced amongst the exercisers? Perhaps people with willpower and self-discipline can lose weight through exercise.

Moreover, could actually knowing that exercise affects your appetite make a difference to the result? In a follow up study we might tell one group of subjects that exercise will increase their appetite and sabotage the weight loss benefits. Could that knowledge elevate those with less will power to a position where they, too, can lose weight though exercise?

Anecdotally, I know this to be possible. A few years ago I lost several pounds by religiously sticking to the types and amounts of food I consumed daily while increasing my weekly running mileage by 15 miles; and I witnessed my gym partner drop nearly a stone in weight over 3 months by the addition 30 minutes of post-weights cardio and a determination not to eat more food than usual.

I’ve nothing against people who want to issue advice that’s most likely to lead to success for everyone – after all, I advocate the Paleo diet, which takes the lowest common denominator approach to nutrition.

So if you have to chisel something onto a stone tablet, then yes,

Exercise is not the key to weight loss: it’s mostly about what you eat

…would be the best thing.

However, it would be nice to see more recognition by both commentators and researchers that humans can apply free will in this matter.


Anonymous said...

Total agreement here. Before going paleo, I tried to lose just half a kilo or so and while I made some progress it was really hard and very much a matter of willpower. As soon as I started eating paleo, I lost that weight without even trying.

Asclepius said...

"Perhaps people with willpower and self-discipline can lose weight through exercise."

I think they can - but for the reasons that i) exercise can upregulate insulin sensitivity ii) willpower can make you push on with a diet & exercise regime, even in a state of 'semi starvation'.

It would be nice to see the 'bodpod' stats and 'bloods' of those that embark on weight loss "regardless of the type of exercise they are doing or food they are eating". Are they losing fat or muscle and bone as well? The other thing is how sustainable this 'regardless' approach is?

Far from 'over-eating' or being 'under-active', the obese are in a 'perfect balance' at a cellular level because the cells are making the person eat at a level where the energy requirements at the cellular level are being satisfied.

If you don't address nutrition at a cellular level then even if you lose weight, you are not addressing the underlying problem and you will always be fighting the gain!

Kat Eden said...

"I believe that if someone really wants to lose weight with exercise, then they will, regardless of the type of exercise they are doing or food they are eating."

I think you've hit the nail on the head with this line. While the type of exercise (weight-based circuits are best IMO) and the food quality (definitely NOT the high-carb rollercoaster!) play a huge part in weight loss, it really does seem in large part to come back to the beliefs and determination of the person.

I've seen people eat rubbish some of the time and still lose weight because they absolutely believed they could and would. And I've seen plenty of others do 'all the right things' and get nowhere. Funnily enough, these are the people who - when questioned - admit that they don't really think it's possible.

Of course exercise can assist in weight loss. It's certainly not the be-all end-all, and there are most definitely many additional factors which must be paid due attention, but using a broad statement such as "it increases appetite" to claim it doesn't work is somewhat ridiculous.

Paleo Garden said...

I think you bring up some interesting things to think about here. I think that the optimal is eating paleo with good random workout routines. Perhaps, the question you raise can also be looked at regarding whether for some people trying to take on both, which is better for them to try first if baby steps are needed. Eat paleo first? Or work out first, then after feeling good effects of physical activity trying to eat paleo? I think for some people who are inexperienced in both healthy eating and working out trying to do both for the first time can be intimidating.

Methuselah said...

madMuhhh - yes, it does seem like the amount of willpower required is in proportion with the correctness of the diet.

Asclepius - good points, with which I agree. Losing weight with the wrong diet or the wrong kind of exercise does diminish the quality of your body composition. And it makes it harder, so more willpower is required. But if you are already eating a strict paleo diet and have reached equilibrium at good body composition, but you want to become leaner, there is nowhere to go with your diet except by eating less. Assuming you are already exercising to some extent, this amounts to exercising more. Alternatively you could carry on eating the same amount but exercise more (in a paleo-friendly way, such as long vigorous walks.)

Either way, you could argue that the exercise is stimulating the appetite and that you must use willpower to resist the temptation to eat more. In this scenario in fact it seems like it's all about the exercise and less about diet...just thinking out loud - what do you think?

Kat - you're right about how people appear unable to lose weight despite apparently doing the right things. I have seen my training partner be successful at some times and not at others - it's all about his state of mind at the time.

Paleo Garden - good thoughts. I think the best thing for beginners is to start small with the diet and the exercise at the same time. Then they slowly build up a complete picture as they go along...

David Moss said...

I agree that people can lose weight simply through increase in exercise while holding food-intake stable, but isn't this essentially just based on the fact that if you (by force of willpower, overpowering their biologic drive to homeostasis) create a net calorie deficit then you will lose weight? In this sense the more exercise route to caloric deficiency doesn't sound much more hopeful than the forced starvation to caloric deficiency.

That said my personal view has always been that more exercise is almost certainly positive*. I never understood the conclusion from Taubes that insulin is what counts, therefore exercise doesn't matter. Continuously glycogen-depleting the muscles seems a massive boon to weight loss: esp since relative insulin sensitivity of fat/muscle is so important.

I must confess I also always thought that exercise reduced appetite (which seemed true to my experience) as per this study but I've never looked into it properly. Both sides have some intuitive backing: on the one hand you'd expect the body to demand enough calories to meet its needs, but exercise does force energy out of storage and into the bloodstream. Perhaps suitably intense exercise if you're leptin responsive and have adequate fat stores alleviates appetite, but in a leptin-resistant or starved state it leads to increase in demand for calories?

Methuselah said...

Hi Dave,

I agree there is much of a difference between calorie reduction and exercise increase when the composition of the diet remains the same - I feel it amounts to the same thing. I think where the willpower comes in is in overpowering homeostatic forces until they reset. I am not an expert by any means on the hormonal forces affecting how our body stores fat and regulates appetite, but I do know that I existed comfortably at 11% fat for a few years, before existing comfortably at 17% fat for a few years. In between the two was a sustained period of calorie deficit, during which I was permanently hungry. I was then determined not to regain the fat once I had lost it, so my hunger continued once I was 11%, but gradually subsided, allowing me to then rest at that level and eat according to my hunger.

Drs. Cynthia and David said...

I think you're right that motivation and attitude is also key- it helps establish the habits that make or break the weight loss effort. One time when I was successfully losing weight, whenever I would get hungry, I'd try on clothes to see which ones fit again, and the hunger would vanish. Of course that doesn't work so well when you're discouraged with your progress.

When upping the mileage a couple months ago (>50 miles/week), I found I literally could not eat enough to keep my weight constant, even though I was eating extra, and some carbs too. But most caloric expenditure can easily be kept up with by eating just a little extra, and then any habitual eating at that level that isn't balanced by exercise will start putting the pounds back on. In my case, the weight loss halted when the mileage came back down to customary levels (an injury wouldn't let me keep it up), and luckily it didn't reverse (much), mostly because I recognized that I had to stop the extra feeding.


Methuselah said...

Cynthia - I think consciousness is the key here. You mentioned that you moderated your eating because you were conscious of ('recognized') needing fewer calories. It seems like a lot of the time it is assumed that people are not conscious of the effects of exercise on their diet. Yet if you know to resist the effects of exercise on your appetite, the effect is in turn diminished or at least your susceptibility to it is.

Primary Work at Home said...

I agree, the surest way to make us thin is through exercise and diet.

Blog Widget by LinkWithin