Spoon‑Fed: Why Almost Everything We’ve Been Told About Food Is Wrong (Tim Spector, 2020)
“As we gain a better understanding of the different components of food and how they interact together, some calorie-content estimates are emerging as inaccurate or outright wrong.
Walnuts, for example, spent years with their calorie content inflated by 20 per cent on food packaging until it was discovered that much of the fat they contain is not released when we eat them.
Almonds have been similarly over-estimated in calorie content by about 31 per cent.
Another good example of this is corn: how the body uses and stores the energy gained from a food as difficult to digest as corn on the cob is very different to how it uses energy from corn bread or from cornflakes processed by superheating, pressurising and roasting.
Yet the simplistic calorie intake theory treats the energy gained from each as the same.
We also now know that the way that food is cooked alters its structure and therefore how much energy it provides — so a raw beef-steak tartare will provide fewer calories than a bloody burger cooked rare, which will provide less than a well-done charred one. (…)
To confuse things further, foods interact, and their calorific content varies when mixed, so the rate of energy released from a cheese sandwich, for example, may be different from the value of the bread and cheese measured separately.
Even more importantly, the ultra-processed nature of modern food generally means that the complex structure of the plant and animal cells is destroyed, turning it into a nutritionally empty mush that our body can process abnormally rapidly.”