Is walking enough exercise? Daniel Lieberman's answer

On the ZOE Science & Nutrition podcast (November 2023), host Jonathan Wolf asked Daniel Lieberman, an evolutionary biologist at Harvard who studies how humans came to move, whether just walking would be enough activity. In that conversation, Lieberman questioned the word "sufficient" and answered a more useful question instead:

"whatever you do is better than none... if you're going to do anything, walk"

Daniel Lieberman, ZOE Science & Nutrition, 2023

Why "enough" is the wrong question

"Is walking enough?" assumes there's a pass mark, a line above which exercise counts and below which it doesn't. Lieberman's point, earlier in the same stretch of the episode, is that no single amount fits everyone. It depends on your age, your fitness and what you're hoping for. What holds for nearly everyone is simpler: some activity beats none, more brings more, and the extra gains tend to level off.

Walking, Lieberman says, is the most basic form of physical activity. If all you can do is walk, that's fine. If you have the time or the inclination, a little more vigorous activity and some variety are worth adding. Walking isn't a lesser version of exercise that you have to graduate from before it counts.

What the guidelines say

Public guidance agrees with the first half. The UK Chief Medical Officers put it as "any activity is better than none and more is better still", and add that the biggest gains come from going from inactive to fairly active, even below the full weekly direction (UK Chief Medical Officers, 2019).

That direction is about 150 minutes a week of moderate activity, and brisk walking is the guidelines' own first example. The NHS gives a simple way to tell moderate from light: at a moderate pace you can still talk, but not sing (NHS, 2024). A stroll where you could sing along to the radio still counts as movement. It just sits at the lighter end.

The minutes don't need to come in one block. A review of 19 trials with 1,080 people compared one long session with the same exercise split into shorter pieces, and fitness and blood pressure came out the same either way (Murphy et al, 2019). So a ten-minute walk is a real session.

Advice on checking first differs. The NHS suggests speaking to your GP if you haven't exercised for a while. WHO and US guidance say that for light to moderate activity, like brisk walking, that's generally not needed. If you get chest pain when you're active, have a heart condition, or a doctor has told you to limit your activity, check first. If checking would put your mind at rest, do.

If your question is really about walking and weight, that's a separate one: see walking for weight loss.

How this fits the Build an exercise routine program

In the 1h Protocol to Build an Exercise Routine, one of the outcomes of the free first chapter is the Tune-up, for people with no single obstacle, and its first step is exactly this: a ten-minute walk at a pace where you can talk. The paid chapter "What counts" goes through why any movement and any length count, with Lieberman's view in a note, then has you set your full version, your short version for hard days and your weekly number. Four one-tap check-ins follow by email on days 1, 7, 14 and 30, if you're signed in. The first chapter is free.

Source: ZOE Science & Nutrition, Exercise myths busted with Prof. Daniel Lieberman, 23 Nov 2023, at 54:15 Research: UK Chief Medical Officers, 2019 · NHS, 2024 · Murphy et al, 2019