The body does not treat all calories alike

One of my good friends and I occasionally discuss whether all calories are alike.

His perspective on losing weight involves eating less, full stop.

Mine involves eating the right kind of foods, which the body has to work harder to digest.

On Monday, June 20, 2022, an article appeared in the Daily Mail, ‘Counting calories is a waste of your time, says gut health guru Dr Megan Rossi’.

Here is the essential part of the article (emphases mine):

… with highly processed foods, most of the food matrix has already been broken down for us by machines, making the calories more accessible (so the figures on the labels for ultra-processed foods are a more accurate measure of what our body absorbs).

Another reason for not focusing on calories is that not all calories are equal, because of food’s thermogenic effect. This is when you burn calories while eating and digesting. In other words, your body’s processing will counter some of the calories — and here’s the important bit — depending on the specific food.

Whole foods such as fruit, veg and nuts that need chewing, breaking down and more digesting have a higher thermogenic effect than ultra-processed foods.

And the calories from highly processed foods are much more readily available. For example, a KitKat and a banana might contain similar calories and your food-tracking app won’t treat them any differently — but your body will.

One study in particular (published in 2010 by Pomona College, Claremont, in the U.S.) found that the body burns nearly 50 per cent fewer calories digesting a meal of processed foods than after a whole-food meal, even if both contain the same total of carbs, fat and protein.

It might not sound enough to make a lot of difference, but over a month, a year, a lifetime, it certainly adds up.

Further research in the journal Cell Metabolism in 2019 found that people told to eat as much as they liked gained more weight when given ultra-processed foods than when having unprocessed options — again, even when the meals were matched for carbs, fat and protein.

This supports what I’ve seen in clinic: limiting processed foods is a better weight-management strategy than counting calories.

These sorts of findings are repeated time and time again, and explain why we often don’t experience a lasting feeling of fullness after eating processed foods. For instance you might feel stuffed after a fast-food meal, yet weirdly ready to eat more an hour later.

If a food has already been broken down for you, your body has less work to do and it’s less satisfying. An apple takes longer to eat and is way more filling than apple sauce, which itself is more satiating than a glass of apple juice. That’s because a whole fruit contains fibre and water bound up in that food matrix.

Unlike me, Dr Rossi is big on plant-based diets. However, she did have something interesting to say about gut bacteria, which she says is a:

secret weapon … These, and the chemicals they make when they digest plant fibre, can affect appetite.

These chemicals, such as short-chain fatty acids, tell our body we’ve had enough. This halts the production of hunger hormones such as ghrelin, and increases the ‘I’m full’ hormones such as leptin.

Other chemicals produced by our gut microbiota are thought to target the reward network in the brain, which influences our relationship with food and our tendency towards emotional eating.

Microbes and their by-products have also been linked with ‘turning on’ genes related to fat distribution. Added to the fact that our microbes may influence our taste receptors, it’s pretty clear that having a higher body weight is way more complex than simply eating too much and not exercising enough. So feed your gut microbes and it’s likely to keep everything else in check.

This is why it is important to prepare meals from scratch. Even at my busiest during my working years, which included being in the office at the weekends, I always made time to prepare two sets of dinners for the days ahead. I could take one portion out from the freezer every day and put it in the refrigerator. It was thawed by the time I got home that evening.

Ready meals never gave me as full a feeling, so to speak, as homemade dinners did.

The same goes for treats, such as cakes and biscuits. Baking with butter and sugar produces a more satisfying result than buying something off the shelf made with vegetable oil and corn syrup. Consequently, one eats less of a homemade sweet treat than an industrial product.

The answer to obesity is to eat fewer processed foods, especially carbohydrates, and to focus on natural fats and proteins instead.

The ketogenic diet is a way of eating, for life. It makes food more enjoyable and satisfying.