Burn Fat Fast: How Much Cardio Do You Really Need?

The human body begins to utilize stored fat as an energy source within the first minute of cardiovascular exercise, according to Brazilian physical trainer Márcio Atalla. This finding challenges the long-held belief that at least 30 minutes of aerobic activity are required to initiate fat burning.

Atalla’s research, reported by O Globo on March 21, 2026, indicates that after 1.5 minutes of cardio, approximately 50% of the energy expended comes from fat reserves. This percentage increases to over 90% after three minutes of sustained activity. The trainer emphasized that exercises engaging multiple muscle groups, such as running, swimming, and rowing, are particularly effective for weight loss due to their higher caloric expenditure.

The findings align with previous research published by O Globo in July 2024, which confirmed that cardio exercises burn more fat than weight training, although weight training does boost metabolism. That earlier report noted that both intensity and duration are key factors in achieving results.

According to a July 9, 2024, report in O Globo, Atalla stated that the body’s ample fat stores create it a more efficient energy source than glucose during exercise, contributing to the rapid shift towards fat utilization. The report also highlighted the importance of both time and intensity in maximizing fat burn.

While running, swimming, and rowing are highlighted as efficient cardio options, the overall principle remains consistent: the longer the aerobic activity, the greater the caloric expenditure and, the more fat burned.