Six months ago, I laced up my trainers, stepped outside, and did something my running club friends found mildly scandalous: I Stopped running. Not because of injury, not because of laziness, but because I wanted to see what would actually happen to my body composition if I swapped high-intensity miles for a daily brisk walk. What followed genuinely surprised my trainer, and honestly, it surprised me too.
Key takeaways
- A runner swapped their usual 5km runs for daily brisk walks and tracked what happened to their body
- The results challenged their trainer’s assumptions about intensity, calories, and fat loss
- Walking triggered less post-exercise hunger, leading to naturally better eating patterns
Why I made the switch
Running had been my go-to for years. Three or four sessions a week, around 5km each time, nothing extraordinary but enough to feel like I was “doing cardio properly.” The trouble was the hunger. After every run, I was ravenous in a way that brisk walking never made me. I’d finish a Tuesday evening jog and promptly eat a bowl of pasta large enough to feed a small family. Something wasn’t adding up.
This isn’t just my anecdote. Research published in the journal Appetite has consistently shown that high-intensity exercise can trigger compensatory increases in appetite hormones, particularly ghrelin, which can cause people to unconsciously eat back the calories they’ve burned and then some. The effect varies between individuals, but for a meaningful proportion of regular runners, the post-run hunger is genuinely physiological, not just a lack of willpower. Knowing this made me feel considerably less guilty about my pasta habit.
So I shifted to a daily 45-minute brisk walk instead, aiming for a pace where I could hold a conversation but would feel genuinely warm within five Minutes. No playlists of aggressive music to push me harder. Just movement, at a steady, sustainable clip.
What the body fat numbers actually showed
My trainer, who works primarily with clients chasing fat loss, was sceptical from the start. Her professional instinct, understandable and well-founded in many contexts, was that lower intensity means fewer calories burned means slower fat loss. She’s not wrong in isolation. A 45-minute brisk walk burns fewer total calories than a 45-minute run. Full stop.
The difference, though, showed up in what exercise physiologists call substrate utilisation. At lower intensities, your body preferentially burns fat as its primary fuel source, rather than the glycogen it leans on during harder efforts. This is the basis of the “fat-burning zone” concept, which has been mocked in Fitness circles for years but Actually contains a kernel of genuine truth. The mockery usually comes from people conflating “burns more fat as a percentage” with “burns more fat overall,” which are very different things depending on context and duration.
After three months, my trainer did a body composition assessment. My overall weight had barely shifted, which was the part she expected. What she didn’t expect was that my body fat percentage had dropped by 2.1%, while my lean muscle mass had stayed essentially stable. Running, for me, had been subtly eating into muscle, likely because the post-run hunger was leading me to over-eat carbohydrates rather than adequate protein. Walking didn’t spike my appetite the same way, so my diet became naturally more consistent without any deliberate restriction.
She looked at the numbers for a long moment. “I’m going to have to rethink some of what I tell clients,” she said.
The underrated case for walking more and running less
Brisk walking, defined as a pace of roughly 3 to 4 miles per hour, has a genuinely impressive body of research behind it. Studies tracking large populations have found associations between regular walking and reduced risk of cardiovascular disease, type 2 diabetes, and certain cancers. A study published in the British Journal of Sports Medicine found that walking at a brisk pace was linked to a 24% lower risk of all-cause mortality compared to slower walking speeds, suggesting pace matters as much as the activity itself.
There’s also something to be said for adherence. Running carries a meaningful injury rate; estimates vary but figures around 50% of regular runners experiencing an injury in any given year appear in the literature with some consistency. Walking, by contrast, is low-impact enough that most people can sustain it daily without the need for recovery days. Six months into my experiment, I had missed perhaps four or five sessions due to genuinely bad weather. When I was running, I was regularly skipping sessions due to fatigue, sore knees, or simply not feeling up to the effort.
The cumulative effect of showing up every day, even at a lower intensity, seems to matter enormously. Consistency compounds in ways that periodic intense effort cannot fully compensate for.
What I’d actually recommend
None of this is a case against running. If you love it, if it works for your body, if the post-run hunger doesn’t derail your eating, then by all means carry on. Running offers cardiovascular benefits and the kind of time-efficient calorie burn that walking simply cannot match if your sessions are short. The two don’t have to be rivals.
What my experiment did challenge is the assumption that harder always means better when it comes to body composition. For some people, particularly those who find high-intensity exercise triggers overeating, dialling back the intensity and increasing consistency may produce better results than grinding through runs they dread and then eating their feelings afterwards.
Aim for a pace where you feel genuinely warm and slightly breathless but can still speak in sentences. Hit 45 to 60 minutes most days. Pay attention to whether your appetite is easier to manage on walking days versus running days. Track the pattern over weeks, not sessions.
My trainer has since started asking new clients about their post-exercise hunger levels before defaulting to a running programme. It’s a small shift in her practice, but one that might change quite a lot for the right person. Which makes me wonder: how many people have quietly given up on fat loss goals not because they weren’t working hard enough, but because the type of effort they were making was actively working against them?
Always consult your GP before making significant changes to your exercise routine, particularly if you have any underlying health conditions.