The energy cost of running, in kilojoules per kilometre, generally doubles what the same distance costs in walking. At a realistic body weight, a 2 km workout would require 350–450 kJ walking at 4 km/h, versus 700–900 kJ running at 9 km/h. That calculation holds whether the 1600 m comparisons are done on a treadmill or a track. Choosing when to walk and when to run depends on more than just the distance-based cost, though, and time, appetite, and joint stress also change the picture.
Distance cost, not just pace
In a 2004 trial, the energy cost of both treadmill and track running was higher than walking to cover the same 1600 m distance at each participant's preferred speed. In a study of 1600 m trials, running required 481 ± 20.0 kJ or 480 ± 23 kJ for treadmill and track, almost 120–130 calories higher than the equivalent energy expenditure while walking, which came in at 340 ± 14 kJ or 334 ± 14 kJ. Running took 3.75 ± 0.39 minutes per 1600 m on the treadmill, versus 9.08 ± 1.12 minutes for walking, but the authors still find a difference in energy cost per distance.
The ACSM equations confirm this same distance-coverage cost difference, even when flattened into equations of oxygen cost. At ACSM’s estimated minimum walking speed of 4 km/h, the equation \(V O_2 = 0.1 \text{ mL} \text{ oxygen} \cdot \text{ kg} \cdot \text{ min}^{-1} \cdot \text{ m}^{-1} \times \text{ speed} + 1.8 \times \text{ speed} \times \text{ grade} + 3.5\) calculates to 12.9 mL of \(O_2\) per kg of body weight for 1 min, under the assumption of no grade. ACSM’s equation for running, using the same oxygen-cost factor but with a different multiplier for gradient, comes in at 23.9 mL \(O_2\) per kg per min when the speed is raised to 9 km/h, or almost twice the walking cost at these same speeds.
The ACSM equations also show the distance difference in straightforward horizontal cost, where the cost per meter of moving horizontally is 0.1 mL \(O_2\) per kg per meter during walking, versus double that during running. Taking speed into account, ACSM’s walking equation calculates to an average of 1.8 mL oxygen per kilogram per minute for every 1 km/h increase in walking speed, where the running equation calls for an increase of 2.0 mL \(O_2\) per kg per min per 1 km/h. Even with its more efficient striding gait, running still incurs a higher modest cost per kilometer compared with brisk walking.
When the hour is fixed
The per-distance cost of running, while higher, must be split over a shorter time span when walking and running speeds are compared. Faster walking burns more calories per kilometer than slower walking, but burns fewer calories per kilometer than a 1 km/h slower run at the same field speed. Those calorie cost differences don't prevent running from delivering a net cumulative gain when time is fixed.
When total time is fixed, as it would be in a straightforward hour-long walking or running interval, running ends up delivering twice the per-kilometer energy cost over a 25% reduction in minutes. Relative to walking, an hour of running yields lower kilojoules per minute but more total energy expended. The ACSM equations recommend a higher objective intensity factor for running than walking, using the same calorie multipliers, but also recommend turning up the speed.
If there is a verified calorie comparison over the same time interval, the evidence points toward a deficit in relative energy intake after running, with a prior study on running versus cycling showing that appetite was suppressed and relative energy intake lowered, while walking versus running has little verified comparative data. Obvious next question: how does appetite respond when comparable intensities are held to 60 minutes and measurements are performed identically for both exercise modes?
Appetite suppressed
Evidence for exercise-induced appetite suppression features clearly in the analysis of walking versus running post-workout.
A 2012 study of eight healthy overweight or obese men comparing running, walking, and rest showed the suppression of relative energy intake at the post-exercise meal by 194 ± 206 kcal after running, 41 ± 196 kcal after walking, and no significant change after rest. No differences were observed after walking, but the running sessions appeared to elevate both the orexogenic and anorexogenic peptides in question, while no changes were observed for the same peptides after walking.
Shedding further light on appetite after exercise, a 2011 review paper on exercise, hunger, and food intake states that 120 minutes of mixed-intensity treadmill running in a fasted state suppressed hunger, acylated ghrelin, and relative energy intake, while absolute energy intake was unaffected. Digging into the metabolic mechanisms, a 2009 study of same-participant running versus resistance exercise found evidence that aerobic exercise suppressed hunger more than resistance exercise after 0.75 and 1 hour, and that acylated ghrelin suppressed during both resistance and aerobic exercise while PYY levels increased during and after aerobic exercise.
In the larger picture, a 2024 review hypothesizes that evidence for exercise-induced appetite suppression remains mostly associated with acylated ghrelin, while a 2014 review table reports no difference in acylated ghrelin and no difference in appetite between a 60-minute brisk walking trial, at about 45.2% ± 2% of \(V O_2\text{max}\), relative to a similar 35.2% ± 3% \(V O_2\text{max}\) walking and rest conditioning.
What the evidence still does not settle
Exercise can influence acute energy balance, but the current verified evidence does not verify an advantage of running over walking in long-term fat-loss, and a wide number of caveats limit any claims about long-term joint stress. Taking 60 kg, 70 kg, and 80 kg body-weight models, ACSM recommends 2.5-8 calories burned per meter walking at 6.4 km/h, or 7-11 calories per meter for that same body mass at 13 km/h, while none of the verified primary sources provide a canonical valuation of "joint load over a training year."
What readers usually get wrong
Appetite does not respond identically after walking and running, and "best for fat loss" does not always mean "highest calories burned per mile." Without a verified comparison of walking and running when intensity, participant, and appetite testing regimens are held equivalent across a similar anchored time, fat-loss gains aren't that simple.
Sized so as not to disrupt metabolism, a bout of walking at about 45.2% ± 2% \(V O_2text{max}\) shows no statistically significant difference in acylated ghrelin or appetite compared with another conditioning bout of walking at 35.2% ± 3% \(V O_2\text{max}\). Those walking results stand in contrast to the lowered post-workout energy intake observed in a several-running regimes, where the appetite-suppressing peptide PYY increased both during and after running. Best for fat loss does not always mean "highest calories burned per mile," and an identical appetite response is not biologically guaranteed.
Bottom line for choosing an hour
Running and walking both burn calories and both suppress post-workout appetite, but the energy cost comparison comes down to distance versus time and medical caveats are plenty when it comes to year-long joint health. Walking burns fewer kilojoules per kilometer and takes longer to complete the same distance, but results in an identical appetite response in an hour-long trial. Current acute evidence of relative energy intake finds a suppression after running, but not walking. There is no verified weight-loss advantage for running over walking yet, and theories of combined exercise have not settled their comparative value for fat loss.
This is health information, not medical advice. We describe mechanisms, numbers and published evidence. What applies to you depends on your history, your medication and your clinician — take decisions with them, not with an article.
H
HCG Health Desk
HCG is written by an independent desk covering weight loss, diets and metabolic health. We do not sell programmes, supplements or injections, and we say when the evidence is thin.
