The Cardio Guide for Fat Loss: Walking vs Running (and How I Use Cardio to Stay Lean Year-Round)
I used to think “real cardio” meant hard running, drenched in sweat, lungs on fire, and if you weren’t suffering, it “didn’t count.”
That mindset lasted right up until I realized two things:
The best cardio for fat loss is the one you can repeat consistently without wrecking your lifting, joints, or motivation.
If you want a lean, athletic look year round, the kind where a six pack doesn’t come and go with bulks and cuts, you need a strategy you can actually live with.
As a natural pro bodybuilder, the goal isn’t just “burn calories.” It is staying lean while still training hard, recovering well, and showing up week after week.
And that’s exactly why the vast majority of my cardio is LISS incline treadmill walking, with a little higher intensity work sprinkled in.
Let’s break down what actually matters with research, the pros and cons of each cardio style, and how you can choose what fits your goals and lifestyle.
1) First: what cardio actually does for fat loss
Fat loss is driven by a calorie deficit over time. Cardio helps by:
Increasing energy expenditure, meaning you burn more total calories per week
Improving cardiovascular fitness so your body feels better during workouts and daily life
Supporting adherence because many people find they diet better and stay more consistent when they are moving more
A huge dose response meta analysis of 116 randomized clinical trials in adults with overweight or obesity found that increasing aerobic exercise was associated with reductions in body weight, waist circumference, and body fat measures, with improvements generally increasing up to about 300 minutes per week.
Important nuance. Cardio works, but it is not magic. Another systematic review and meta analysis looking at isolated aerobic exercise found that aerobic programs produced modest reductions in weight and waist circumference, and that exercise alone tends to be limited as a stand alone weight loss tool for many people. It shines even more when paired with nutrition.
So the smart way to think about cardio is this.
Cardio isn’t the main fat loss plan. Cardio is a lever.
A lever you can pull to create or maintain a deficit, improve health, and make your results more sustainable.
2) Walking vs Running: the honest pros and cons
Running, Pros
Burns more calories per minute, so it is more time efficient
Bigger stimulus for VO2 max and cardiovascular performance, so fitness tends to improve faster
Can be great if you enjoy it, and enjoyment is a cheat code for consistency
Running, Cons
Higher impact and joint stress, especially if you are heavier, newer, or ramp volume too quickly
Recovery cost is higher, meaning more soreness and fatigue and it can interfere with leg training
Higher injury risk if you are aggressive, too much too soon is the classic mistake
Bottom line. Running is an awesome tool when it fits your body, your schedule, and your recovery budget.
Walking, Pros
Low impact and easy on joints
Faster recovery, meaning you can do a lot of it without it beating you up
Easy to stack volume, more days per week and more total minutes and more steps
High adherence because it does not feel like punishment
Walking, Cons
Burns fewer calories per minute, so you may need more total time
Cardio fitness improvements can be slower compared to vigorous modalities, especially if intensity stays very easy
Bottom line. Walking is often the most sustainable base cardio for fat loss, especially if lifting performance and recovery matter.
3) The cardio types that actually matter
A) LISS, Low Intensity Steady State
Examples include incline treadmill walking, easy cycling, incline outdoor walks, and long dog walks.
Why it is powerful for fat loss:
Minimal recovery cost, so you can repeat it often
Easier to keep hunger and fatigue manageable
Great for people who are already lifting hard
This is exactly why it is my staple.
My go to: Incline treadmill walking, my “abs all year” cardio
I love incline treadmill walking because it hits the sweet spot of low impact, high consistency, and higher calorie burn than flat walking because incline increases the metabolic cost.
Research on walking and running slopes shows that energy cost increases on positive inclines, uphill work costs more.
And real talk, it is easy to live with.
I can put the incline up, get into a steady rhythm, and watch YouTube or Netflix. That makes it boring in the best way, boring enough that I can do it consistently for months. And yes, subtle plug, if you want more training and nutrition breakdowns like this, subscribe to my YouTube channel.
Typical LISS setup:
20 to 45 minutes
Intensity where you can talk in full sentences, think RPE 3 to 4 out of 10
Frequency of 3 to 6 times per week depending on goals and phase
And sometimes instead of the treadmill, walking my dogs. It still counts. If it increases weekly movement, it is part of the plan.
B) HIIT, High Intensity Interval Training
Examples include hard intervals on a bike, rower, treadmill, sprints, and assault bike intervals.
HIIT’s biggest selling point is time efficiency and a strong fitness stimulus.
A meta analysis comparing HIIT vs moderate continuous training in overweight or obese adults found that both reduced fat mass and waist circumference, with no major differences between them for body composition overall, while HIIT required about 40 percent less time.
Another systematic review and meta analysis found both HIIT and moderate continuous training improved body composition and cardiorespiratory fitness, with HIIT showing some advantages for waist circumference, percent fat mass, and VO2 peak in their analysis.
Why I only do HIIT 1 to 2 times per week in short bouts is because HIIT is expensive. It creates more fatigue, more soreness risk, and more interference potential with heavy lifting, especially legs.
So I treat HIIT like seasoning, not the main course.
Simple HIIT template, 10 to 20 minutes:
Warm up 5 minutes
6 to 10 rounds
20 to 30 seconds hard, RPE 8 to 9
60 to 120 seconds easy
Cool down 3 to 5 minutes
Pro tip. If you are newer or carrying more body weight, choose bike, rower, or elliptical first. It is usually friendlier on joints than running sprints.
4) How much cardio do I need, the science and the practical answer
The science view, helpful targets
A major ACSM Position Stand notes:
150 to 250 minutes per week of moderate activity helps prevent weight gain
That same range tends to produce modest weight loss
More than 250 minutes per week is associated with more clinically significant weight loss in many cases
The large dose response meta analysis in JAMA Network Open found that increasing aerobic exercise was associated with progressively greater improvements up to about 300 minutes per week, and that around 150 minutes per week at moderate intensity or higher may be needed for meaningful reductions in waist and body fat measures.
WHO’s guideline is at least 150 minutes per week moderate, or 75 vigorous, and up to 300 minutes per week for additional health benefits.
The practical view, what I actually coach
Start from where you are, then progress in a way you can sustain.
A simple progression ladder:
Baseline movement, increase steps and daily walks
Add 2 to 4 LISS sessions per week, 20 to 40 minutes
Add 1 short HIIT session per week if you need time efficiency or want the fitness boost
Adjust volume based on your weekly fat loss rate, hunger, and lifting performance and recovery
5) How I use cardio to maintain a six pack year round
Here is the philosophy behind my approach.
I build my cardio around recovery and consistency
LISS incline walking is my default because it does not crush my legs
I can do it frequently without feeling run down
It helps me keep a higher activity baseline even when calories are lower
I add HIIT sparingly
Usually 1 to 2 short sessions per week, mainly for cardiovascular performance, time efficiency, and mental variety.
A realistic weekly structure, example
4 to 6 days per week incline treadmill walking, 20 to 45 minutes
Daily extra steps from life and often dog walks
1 to 2 days per week short HIIT session, 10 to 20 minutes, optional depending on recovery
This kind of structure is also why walking is so underrated. It is not walking or cardio. Walking is cardio you can repeat forever.
6) The cardio choice framework, so you stop arguing “best”
Ask yourself these 5 questions.
1) How much time do you realistically have?
Short on time, running or HIIT can be more time efficient
Plenty of time, walking and LISS volume is easy and sustainable
2) What is your current fitness level?
Beginner, start with walking flat or incline
Intermediate or advanced, mix styles based on goals
3) How is your joint tolerance?
Knees, ankles, low back flare up from running, choose incline walking, cycling, elliptical
You tolerate running well, it is a great tool
4) Are you also lifting hard?
If you are serious about building or keeping muscle:
Make your base cardio something you recover from easily, often LISS
Use high intensity sparingly so it does not steal from leg days
5) What do you actually enjoy?
Enjoyment is not fluff. It is adherence.
And adherence is results.
7) Common mistakes that sabotage fat loss cardio
Mistake 1, Going too hard on easy days
If your LISS always creeps into “kind of hard,” you will recover worse, get hungrier, and dread it more. Keep LISS truly easy.
Mistake 2, Using HIIT as your only cardio
HIIT is awesome, but it is tough to stack a lot of it. Most people burn out, get hurt, or their lifting performance dips.
Mistake 3, Eating back your cardio without realizing it
Cardio can increase appetite in some people. If you compensate without noticing, fat loss stalls even though you are doing more.
Mistake 4, Ignoring steps
Structured cardio is great, but daily movement is often the difference between “I’m stuck” and “I’m steadily leaning out.”
8) The simplest takeaway
For most people chasing fat loss and wanting to keep muscle:
Make walking and LISS your foundation
Add running or HIIT when it fits your schedule, joints, and goals
Progress cardio like a plan, not a punishment
Because the truth is this.
The best cardio for fat loss is the one you can recover from and repeat long enough for it to matter.