Can you lose weight by running or walking without wrecking your training?
You run or walk a few times a week and you also want to lose a few kilos. That works together, but not at every speed. Whoever wants to lose weight too fast loses their training first and their muscles next.
The speed of weight loss decides everything
Losing weight is an energy deficit: you use more than you take in. Your body draws such a deficit from fat, but also from muscle and from the energy it uses for recovery. The bigger the deficit, the bigger the share that does not come from fat. A kilo of body fat stands, roughly, for around seven thousand kilocalories; a deficit of five hundred a day is then about half a kilo a week.
That is also roughly the upper limit at which training simply carries on. Above it you notice it first in your sessions: the hard work no longer comes off, your recovery pressure stays high, you sleep worse. Whoever wants to go faster pays for it with exactly the things they train for.
Energy availability: what is left for your body
Sports nutrition has a concept for this that goes beyond the calorie balance: energy availability. That is what remains of your intake after the energy of your sessions is taken off, divided by your fat-free mass. With that remainder your body has to do everything that is not sport: make hormones, maintain bone, keep your immune system running, recover.
If that remainder drops too far, the body turns those processes down. The collective name for that is RED-S, relative energy deficiency in sport: a disturbed or absent menstrual cycle, a lower libido, worse sleep, more frequent illness, injuries to bone and tendon, and performance that declines while you work harder. It does not only affect elite athletes; it is the result of a deficit that is too big for too long, at any level.
The practical consequence is simple. On days with a long or hard session your sport costs more energy, and that should be matched by more intake, even when you are losing weight. You make the deficit on the easy days, not on the hard ones.
Protein keeps your muscles in a deficit
In an energy deficit your body breaks down muscle faster, and protein is the only thing that directly counters that. Research on athletes in a deficit points to a higher requirement than without one: the literature mentions ranges of roughly 1.6 to 2.2 grams per kilo of body weight per day, spread across the day.
That spread matters. Muscle building responds per meal, and a meal with too little protein does not switch that process on; roughly 0.3 grams per kilo per meal is a common lower limit, and from fifty or after a hard session a little more. Three or four meals with a real portion of protein do more than one big one at the end of the day.
Protein has another advantage when you are losing weight: it satisfies. A deficit you can sustain is a deficit in which you are not hungry, and protein and fibre are the two best tools for that.
Do not cut in a hard training week
A build-up has weeks that are harder than others. In those weeks a deficit is most expensive: your recovery needs the energy, and the adaptation you want to achieve with that hard week otherwise fails to appear. So plan the weight loss in the lighter weeks, and eat around maintenance in the hard ones.
Concretely: in a week with a long run and a session with hard work, you eat normally on those two days, with carbohydrate before and after the session. The deficit sits in the other five days, and it is small there. Over a month that yields as much as a constant deficit, without your sessions suffering.
Training fasted to burn more fat is a popular detour that yields little. You do burn more fat during that session, but the daily balance decides, and a session on an empty stomach is more often a worse session. What you gain in fat burning, you lose in quality.
Weigh the trend, not the day
Your weight fluctuates from day to day by a kilo or more, and that has little to do with fat. Water, salt, the contents of your gut and the carbohydrate store in your muscles, which binds three grams of water per gram, all move along. After a long session you can be lighter through fluid and a day later heavier through refilling your stores.
A single weigh-in therefore says almost nothing. Weigh yourself at fixed moments, and look at the line over weeks. A trend over six weeks shows whether the deficit is doing what you wanted; a difference between yesterday and today does not. Whoever steers by daily numbers adjusts something every day and achieves mostly unrest.
Walking or running
Per kilometre, running costs more energy than walking, and per hour far more. But you can walk more often and longer without your legs protesting, and it needs hardly any recovery. For someone who wants to lose weight and build a base, a daily walk of an hour is often more achievable than three running sessions of which the third becomes an injury.
The combination works best: running as the stimulus on the days you are fresh for it, walking on the other days as movement that helps the daily balance without loading your recovery. Both count in your load, and both count in what you use.
What Trimetra does with this
Set a weight goal in the app and you choose a speed to go with it. The fastest setting comes down to a deficit of five hundred kilocalories a day, about half a kilo a week; the other two settings are smaller. The app calculates your daily target from your maintenance plus the energy of your logged sessions minus that deficit, so a hard day automatically gets a higher intake. With a weight-loss goal the protein target goes up, to spare muscle mass in the deficit.
The app reads your weight as a trend over the past six weeks, not as a daily number. Only with enough weigh-ins over enough days does it say whether you are falling, stable or rising, and how that relates to the speed you chose. Below a minimum age the app does not apply a weight-loss goal.
The app is not a medical service and this article is not medical advice. If you have had an eating disorder, are pregnant, or have a condition in which weight plays a role, discuss a weight-loss goal with your doctor or a sports dietitian before you start.
Frequently asked questions
How many kilos a week can you lose while training?
Around half a kilo a week is a speed at which your sessions simply carry on. Faster is possible on the scales, but that comes increasingly from muscle and from the energy you need for recovery. Whoever goes slower keeps it up longer and loses less of what they want to keep.
Should I train fasted to burn fat?
No. Fasted, you burn more fat during the session, but the daily balance determines whether you lose weight, and a session on an empty stomach is more often a lesser session. Eat normally, and make the deficit on the easy days.
Why am I not losing weight even though I run a lot?
Often because intake grows along with the hunger that sport provokes, and because an hour of easy running costs less energy than it feels. Look at your weight trend over weeks and at what you eat on rest days; that is usually where the difference sits.
Is walking enough to lose weight?
Yes, if the daily balance is right. An hour of walking a day is a substantial contribution to what you use, needs hardly any recovery and can be kept up. Running costs more per hour, but not if an injury puts you out for three weeks.
Trimetra calculates your daily target from your own maintenance and your logged sessions, keeps the deficit small and reads your weight as a trend over six weeks. In a hard week the app lets go of the deficit, not of your training.