'Eat less, exercise more' is useless advice; Our activity levels are up.

'Toy models' of metabolism and exercise don't work... Something else is going on...

You’ll have often heard the ‘cure’ for obesity is a twofold, easy to implement, behavioural change: just ‘(i) eat less; (ii) exercise more’.

This ‘cure’ is based on a toy model of our energy use: bring the energy you consume in food plus the energy burned through exercise into a negative balance (less food + more activity), and obesity will be ‘cured’ - because you’ll be burning more calories through activity than you take in through eating.

This is not how our metabolism works at all, as we’ll see below. Worse, this advice guilt trips people in all sorts of ways, and sets them up for failure: because this is not how your metabolism works at all (there, I’ve said it twice now). It’s worth saying this three times: eating less and exercising more is bad, guilt-trip inducing advice for weight loss.

Let me emphasise: exercise is very, very good for you, as I’ve written here, here, here previously; ftaod - you should exercise. And see this. But that’s not the point of this piece… read on.

Stable Diffusion Playground https://stablediffusionweb.com/ eat less exercise more is bad advice people in impressionist painting

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The basics

Every cell in your body needs energy from food, as well as oxygen from breathing, to stay alive (we can ignore other complications for the moment). Brain cells, in particular, are especially energy-demanding - they require a continuous feed of oxygen and nutrients provided by the portal circulation from the heart.

Interrupt this circulation for more than a few seconds, and you will fall unconscious; for more than a few tens of seconds, you will start to get brain damage from brain cells dying (again, we can ignore the complications arising of non-programmed cell death for present purposes); for minutes, and you will suffer irreversible brain death, and possibly die.

The same is true for other organs: interrupting the blood supply to the heart itself is a very bad idea, for obvious reasons, as is the narrowing or blocking of the blood supply pumped by the heart to differing organs around the body. Again, the reasons are obvious.

There’s been lots of recent work on metabolism and energy balance - I’ve previously reviewed some of it here:

and here:

Complications

A simplistic way of looking at our energy balance is to compare the calories we take in from food and drinks with the calories we burn through our activities. However, this is neither accurate or sufficient, because lots of things affect how much energy we use and store in our bodies.

We use energy for various bodily functions, such as breathing oxygen, digesting food and absorbing nutrients, pumping blood through our veins, moving our limbs and organs, and maintaining and repairing the trillions of cells that make up our body. We also burn energy when we are infected: our body temperature rises for reasons explained below. Sometimes this temperature rise in response to infection can be dangerous.

tl,dr: body temperature rises in response to infection because:

• The immune system signals to the hypothalamus (at the base of the brain) to increase body temperature;

• Rising body temperature helps fight the infection in various ways. All organisms, including bacteria and viruses, have their own survival temperature range. By raising body temperature, our bodies might go above the survival temperature range infection range of viruses and bacteria, thereby killing them off.

Infections can result in increased local or general metabolic heat production, contributing to a negative energy balance in the infected host - this causes a metabolic “cost”. To make your body temperature go up, your metabolism goes into overdrive, which requires calories. Fever effectively dissipates a considerable amount of energy in the form of heat.

We also gain or lose energy depending on the conditions of our environment, such as the temperature, humidity, altitude, and air quality. These things all impact how our body manages its energy balance and weight.

There’s more (I said this was complicated)

(I’m going to put 1 post per month behind the paywall. If you like what I do, then you know what to do 😉.)