Is cardio or weights better for fat loss?

Both help, and they do different jobs. Resistance training preserves the muscle that keeps your strength and shape intact while you lose weight; cardio adds energy expenditure and improves cardiovascular health. The best fat-loss programmes include both, with nutrition doing most of the heavy lifting.

What each contributes

• Resistance training: Signals your body to retain muscle in a deficit. Without it, a meaningful share of the weight lost can be lean tissue, which leaves you lighter but not visibly leaner.
• Cardio: Burns calories during the session, improves aerobic fitness and heart health, and is easy to recover from at moderate intensity.
• Daily walking: Often contributes more total energy expenditure than either, simply because there is so much more of it.

Why nutrition still dominates

An hour of moderate cardio might expend a few hundred calories, which is easily replaced by a single snack. Training is far more valuable for what it protects and builds than for what it burns. Treating exercise as a way to create the entire deficit usually leads to excessive volume and poor recovery.

A sensible weekly structure

Two to four resistance sessions covering the main movement patterns, one or two easy aerobic sessions, and a daily step target is a complete and manageable plan. If time is limited, prioritise the resistance training, since the muscle-preserving effect is the part that cannot be replaced.

Will cardio cost you muscle?

Not at normal volumes. Interference becomes a real concern only with high volumes of hard, high-impact cardio alongside heavy lifting. Separating sessions by several hours, choosing lower-impact modes such as cycling or the rower, and eating enough largely resolves it.

Choosing the cardio you will do

Mode matters far less than consistency. Walking, cycling, rowing, swimming, and skipping all work. Pick something you can do several times a week without dreading it, and keep most of it at an easy, conversational intensity so it does not interfere with your lifting.

The training side is covered in Principles of Strength Training and the energy side in Exercise Physiology and Energy Systems.