Is walking better than HIIT for fat loss after 40?

Part of the reason is simple math. Nikkiey explains that formal exercise makes up only about 5% of your daily calorie burn, while non-exercise movement like walking, stairs, cleaning and carrying groceries makes up about 15%. After a hard 45-minute cardio session, your body compensates. You get hungrier, you're tired, and you sit more, so the net burn is smaller than the machine says. Walking doesn't trigger that same response. Your appetite stays steady and you keep moving normally, so 10,000 steps often burns more overall.

The other reason is stress. In her episode on being toned at 60, Nikkiey says LISS (low-intensity steady-state cardio) and HIIT burn about the same calories by the end of a session. HIIT's main advantage is that it takes less time. HIIT adds stress to a body that is already stressed by life and training, and she notes that cortisol is a fat-storing hormone. If your life is high-stress, she would not recommend HIIT. For women 50 and older, and really any age, she recommends LISS, which can just mean walking outside. In her own experience, replacing intense cardio with walking left her more recovered, calmer and less inflamed, and she says her hormones started to regulate. That is her story, not a medical promise. If hormones or menopause symptoms are part of your picture, work with your doctor.

The episodes differ a little on whether HIIT belongs at all. Her 20-pounds episode includes one or two short HIIT sessions a week. The toned-at-60 episode leans toward LISS all the time. Both agree on the main point: neither walking nor HIIT should carry your fat loss. The gym is for building muscle, ideally with three to four strength sessions a week. If you've been doing HIIT every day and the fat isn't moving, Nikkiey's view is that the plan is the problem, not you.