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.)
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:
- 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.
- How strong was their willpower?
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?
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.