Sigh.

In another clickbait Diary of a CEO social media snippet, Jason Fung said:

“Eating fewer calories will automatically lead to weight loss is completely false”.

So, here is what you need to know.

It is totally true; when you reduce how much you eat (calorie intake) your body can respond by reducing how much energy it burns (calorie expenditure). This is a topic intertwined with 'metabolic adaptation' or 'adaptive thermogenesis' where your metabolic rate reduces as you lose weight, sometimes by slightly a disproportionate amount.

But, it is very important not to exaggerate this to make it sound scarier than it really is.

If you weighed more than you do now, your body would have higher energy needs. Likewise, if you weighed less than you do now, your body would have lower energy needs.

Just like you give more food to big pets and less food to small pets. Bigger animals tend to require more food.

Many people exaggerate this to imply that reducing your calorie intake DESTROYS YOUR METABOLISM and the data to support that is not there. It is possible that aggressive weight loss plans may lower your metabolic rate by a disproportionate amount, but it’s still very much equivocal as newer research disputes this theory.

As an example, Jason Fung has said in the past that if you reduce your calorie intake by 500 your body will burn 500 fewer calories and you won’t lose weight.

But, this implies your body will IMMEDIATELY reduce how much energy it burns, which is not true. It reduces in tandem as a consequence of you losing weight. It doesn’t immediately prevent weight loss.

Most importantly, this adaptation to weight loss is often used as a sales pitch to sell you another plan, as if low-carb diets and intermittent fasting plans somehow bypass these metabolic changes.

But they don’t.

Does that make sense?

P.S. My best-selling book, ‘Everything Fat Loss’ is currently on sale as a brand-new audiobook, plus digital/print versions from Barnes and Noble, Apple, Kobo, Google, and Amazon with an extra 10% off in the USA and an extra 37% off in Canada. Feel free to grab it before the price goes up.

http://geni.us/EverythingFatLoss

References:
- What is the required energy deficit per unit weight loss?
- Metabolic Adaptations to Weight Loss: A Brief Review
- Caloric equivalents of gained or lost weight
- The energy cost of walking before and after significant weight loss
- Meta-analysis of resting metabolic rate in formerly obese subjects
- Changes in Energy Expenditure with Weight Gain and Weight Loss in Humans
- Quantification of the effect of energy imbalance on bodyweight
- Physiological responses to slimming