Why weight loss stalls, and why cardio alone makes it worse

The plateau is not you failing

You cut calories, you do the same forty minutes on the same machine, it works for two months, then it stops. You do more of the same. It stops harder. Everyone you know has a theory and most of the theories involve you being lazy.

Here is what is going on. Two adaptations are running at the same time, and both of them are your body doing its job.

Your body gets cheaper to run

Lose weight and your body lowers the cost of keeping you alive. Six years after the Biggest Loser competition, contestants' resting metabolism was still around 500 calories a day below what their size predicted.¹ That's an extreme case from an extreme diet, but the direction is the same for everyone: the deficit you started with shrinks as you shrink.

Your body gets better at the workout

Repeat a movement and you get more efficient at it. That's what practice is. Trained runners burn less energy per kilometre than novices at the same speed.² Efficiency is wonderful for a marathon and terrible for a plateau, because the forty minutes that cost you a lot in January cost you less in April, and you didn't change anything.

The same workout plus the same diet equals a smaller and smaller result. That's not a plateau. That's arithmetic.

Why strength training is the answer

Lifting changes the stimulus, so the efficiency trap resets. It also defends the tissue that burns the calories: muscle is what you lose when you diet without lifting, and losing it makes the first adaptation worse. And the numbers on the bar go up, which is the one form of progress the scale can't take away from you.

This doesn't mean no cardio. It means cardio isn't the tool for the job you've been asking it to do.

The person this is for

The one who did everything the gym told them and got heavier. That person is not undisciplined. They were handed a plan that had an expiry date nobody mentioned.

What to do this week

Two strength sessions. Protein at every meal. Keep one cardio session if you love it, and change it every few weeks so your body can't settle in. And stop weighing yourself daily; see why the scale lies.

End of story. If you'd like someone to write the program around the knee or the back you've been protecting, that's most of what I do.

1. Fothergill E et al., "Persistent metabolic adaptation 6 years after 'The Biggest Loser' competition," Obesity, 2016.

2. Barnes KR, Kilding AE, "Running economy: measurement, norms, and determining factors," Sports Medicine – Open, 2015.