I’m halfway through Tim Spector’s excellent book Spoon Fed, which is a bit like a food and nutrition version of my 2012 book Deceived Wisdom in which he debunks pretty much all of the myths we’ve been told over the years about cholesterol, fat, caffeine, gluten, reduced-fat foods, diet drinks etc.
Spector points out that we are all different, our genes play a major part in our response to food and that most of the claims about this or that food or drink are mainly driven by the marketing departments of the food and drink manufacturers who spend millions on advertising and lobbying policymakers to put messages out there that fundamentally conflict with good advice to sell more of their products.
One of the big myths Spector debunks is with regard to exercise and weight loss. The bottom line, as it were, is that we should exercise for general physical and mental health, but exercising does very little to help you lose weight. In fact, exercising may see you gain weight as you add muscle mass but more likely because it makes you hungry and you end up eating more than you need to after exercising (often in the form of “health” smoothies, protein bars, energy boosters and the like). Your body also slows your metabolic rate after exercise in the short term so that you end up storing more of your food intake as fat.
On what basis does he make this claim? Well, in one sense basic thermodynamics, but he puts it more simply in terms of the way the body uses energy.
We get all of our energy, 100% from food.
We “burn” 70% of that energy just saying alive, metabolic resting rate.
10% of our energy is used to digest the food we eat.
20% is used for physical activity. However, 10% of that is used just sitting, standing, or fidgeting.
The last 10% of the energy we burn can be manipulated through exercise. That’s a tenth of the energy we take in being available to us to burn through exercise.
If you’re an average overweight bloke running an hour a day four times a week, then at best you can knock off 2 kilograms a month. That sounds great, I could get to my ideal weight within a year doing that. But, in order to make this work, you have to NOT overcompensate for the fatigue by eating or drinking more and you have to avoid the extra storage, the slowing of metabolism and the bounceback if you lapse on your calorie counting (You have to be strict with yourself and not eat more even if you feel tired and hungry). It’s mostly sugary-rich food and obesity in a bottle smoothies that are the problem…and alcoholic beverages.
Exercise is a potent drug we all need to take in moderation regularly. Moderate exercise is not a weightloss drug. The only way to lose weight is to eat less and to choose foods better matched to your own metabolism and gut microbes, Spector writes. (There are exceptions to the rules, in the same way that everyone knows a chainsmoking whiskey drinker who died in bed with their mistress aged 97.
As to all that nonsense about 10000 steps? Well, that spurious health notion was invented by a Japanese company that made and sold pedometers in the 1960s…based on nothing more scientific than that 10000 is a nice round number and although it is quite large it is not unachievable in a normal day for a lot of people. But, recent studies have shown that people using pedometers and smart health watches and the like actually gain more weight over the course of a year than those who don’t use these gadgets.
If you’re overweight it would seem that you can’t win…unless you eat less…you can win, if you eat less. It’s not the calories out that count, it’s really just the calories in.