The surprising truth about why we got fat

18 February 2016

Processed foods

I have always had a simple view about the rise of obesity, probably in common with most people who actually weren’t suffering from the problem personally.

You eat too many calories, you move around too little, you get fat. End of story, except maybe for the tiniest percentage of people for whom something chemical is going on.

I even “proved” this to myself a decade ago, because I allowed myself to become overweight. One day it was time to buy some new clothes, and my usual size just didn’t fit me any more. “You just have to accept that you’re now a larger size” my then wife told me.

That was the wake-up call. I decided I wasn’t prepared to cross that threshold without a fight. I began a sensible diet. I went running every day. The weight began to come down. I got into the habit of weighing myself every day and checking if I crossed what I considered to be an acceptable threshold so I could bring myself into line.

It was a bit of a bugger. The clothes I’d bought no longer fitted me. But hey, sacrifices eh?

It’s not just about the number of calories, but the source of where those calories come from

But the point was that it worked. I have stayed within my healthy range ever since.

A piece in the Times today by Jenni Russell throws all of that up into the air for me. (Behind a paywall, sadly, but a sub to the Times is well worth the money). 

A short summary of the case.

In Britain and the US, in the mid-1980s, obesity rates had held steady for 20 years. Then they took off, going into a steep climb. It affected every age group. It happened 5 years later in the UK, but the trend was similar. 

But declines in physical activity, although they were happening, were happening much more gradually, as you might expect. In the UK, the number of calories people were consuming did not significantly increase, indeed the reverse. Calorie intakes did go up in the US.

So if changes in calorie intake and exercise don’t fully explain the change, then there must be other factors at work.

Scientists at York University in Toronto found that, in 2006 people who were eating that same number of calories as their equivalents in 1988 were 10 percent fatter. So people started scouting around for an answer.

The one that is emerging as the favourite is to do with the types of food we’re eating. Modern diets with lots of processed foods, transfats, artificial sweeteners and goodness knows what else, generally have been shown to have a negative impact on the “good bacteria” that live in our guts.

The Cadbury Smash robots
The Cadbury Smash robots - the last laugh is on them

So it’s not just about the number of calories, but the source of where those calories come from.

In the 1980s, people began to move away from natural products (because they were thought unhealthy!) such as butter, full fat milk, eggs and so on. And instead we gorged on snacks, sugary drinks, ready-meals and so on.

I can imagine. As a child, I was brought up on Cadbury Smash instant mashed potato, and all sorts of other modern miracles of convenience. Although fortunately, because my dad was a keen gardener, there were plenty of fresh vegetables in there as well.

But additional research into the effect of these intestinal microbes definitely supported the contention that lots of ‘good’ microbes = healthy weight, but the ‘bad’ microbes from the guts of people whose poor diet had ravaged their internals = fatter. 

The implications of this are good news in principle. For people who struggle with diets, in principle some progress can be made by eating different, not necessarily eating less. Replace processed food with natural foods, lots of variety, cook things yourself (if you’re time-poor it’s easy to build up a staple of ten quick, tasty, healthy recipes you can rely on).

Having slipped into bad ready-meal habits myself in the last year, it was one of my new resolutions this year to cook all meals for myself at home, so this is a timely reinforcement.

Professor Tim Spector
Professor Tim Spector

And I must say I decided some years ago to eat butter, eggs, full fat milk because of the number of stories that were then contradicted years later. I decided that eating natural foods in good variety and moderation would probably see you right, regardless of how much cholesterol scientists thought eggs had (now understood not to be a problem) or saturated fat contained in butter (now understood not to be a problem) and so on.

This may be one reason why so many British people are changing their diets. Nearly a third of the population have reduced the meat consumption over the last year according to the British Social Attitudes survey. The majority are doing this for health reasons, with cost saving and animal welfare concerns also strong in there.

People who are still eating meat are making it go further, extending meat by using it in a sauce, as for Spaghetti Bolognese, where it can be stretched further being mixed with veg.

You’ll notice that the reasons given for the switch have nothing to do with “because it’s a more sustainable lifestyle”. I don’t mind that. If these sorts of changes are genuinely going to become mainstream, it has to be because it is the desirable thing to do, not because it’s some hairshirt fallback that we get forced into against our will.

The scientist who did the research, Tim Spector, produced a list of ‘good foods’ that our gut bacteria love. Jerusalem artichokes. Leeks. Garlic. Lentils (and chick peas). Apples (and bananas). Nuts. Yoghurt. Extra virgin olive oil. Oh, and red wine and dark chocolate. And if you're going to eat meat, it's good to avoid meat that has been routinely fed antibiotics - eg. organic meat or wild game.

See? No hairshirts here!