Cardio is not what makes you lose fat – a calorie deficit is. Cardio is simply one way to widen that deficit. Understanding that changes how you use it: as a tool you dose deliberately, not a punishment you do more of when the scale sticks.
Diet first, cardio second
An hour on a treadmill might burn 400-500 kcal. Two chapatis with ghee is the same number in three minutes of eating. That is not an argument against cardio – it is an argument for fixing intake first, then adding cardio to extend the deficit once food is already controlled. If you have not set your intake yet, start with our calorie deficit guide.
LISS vs HIIT: the honest comparison
LISS (low intensity steady state – brisk walking, easy cycling) burns fewer calories per minute but costs you almost nothing in recovery. You can do a lot of it without affecting your lifting.
HIIT burns more per minute and is time-efficient, but it is genuinely hard training. It competes with your leg sessions for recovery, and the much-discussed “afterburn” effect is real but small – typically under 10% of the session total, not the transformative number often claimed.
For most people dieting while lifting, the answer is mostly LISS with at most one or two short HIIT sessions a week.
How much to actually do
- Starting out: 7,000-9,000 steps a day and no formal cardio. Daily movement outperforms scheduled sessions for most beginners.
- Fat loss stalling: add two or three 25-30 minute LISS sessions per week before you cut calories further.
- Deep in a cut: up to four or five sessions, but keep them low intensity and away from leg days.
When cardio starts costing you muscle
The “interference effect” is real but usually overstated. Problems appear when cardio is high-intensity, high-volume, and placed close to lifting sessions – particularly running, which shares the same muscles and joints as squatting. Cycling and walking interfere far less.
Practical rules: keep hard cardio and leg training at least six hours apart or on separate days, never let cardio compromise the quality of a lifting session, and if you are losing strength week on week, reduce cardio before reducing protein.
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Frequently asked questions
How much cardio should I do to lose fat?
Start with daily steps rather than formal sessions – around 7,000 to 9,000 a day. If fat loss stalls, add two or three 25 to 30 minute low intensity sessions per week before cutting calories further. Most people never need more than four or five sessions weekly.
Is HIIT better than steady state cardio for fat loss?
Not meaningfully for fat loss itself. HIIT burns more calories per minute and saves time, but it competes with lifting for recovery. The afterburn effect is real but small, typically under 10% of session calories. For people lifting while dieting, mostly low intensity cardio with at most one or two HIIT sessions per week works better.
Does cardio kill muscle gains?
Only at high volumes and intensities placed close to lifting sessions. Running interferes most because it shares muscles and joints with squatting; walking and cycling interfere far less. Keeping hard cardio and leg days separate, and reducing cardio if strength drops week on week, avoids the problem.
Should I do cardio fasted?
Fasted cardio offers no fat loss advantage once total daily calories are matched. Do it fasted only if you personally find it more comfortable, as some people perform worse without food beforehand.