Weight Loss and Energy Deficit During Cardio
Key Points;
• Food intake during cardio exercise is best for people who want fat loss but are trying to preserve muscle
• No food intake during cardio exercise is best for subjects concerned with rapid weigh loss
• Weight loss and fat loss is observed either way, but much faster in subjects who do not replace the energy lost during cardio exercise.
• No food intake during exercise is vital for obese subjects to get blood triglycerides lowered.
New research into the effects of replacing the energy used up during cardio exercise gives us some insight into the best strategy for you depending on your weight loss and muscle loss goals.
The University of Glasgow recently studied 13 overweight men to determine the impact of replacing the energy used up from cardio exercise (i.e. eating during exercise) or not replacing the energy used up (not eating)
Not replacing the calories used during cardio exercise had a clear advantage for weight loss and fat burning, but interestingly, subjects replacing the calories used during exercise also experienced weight loss, although at a much slower rate.
This would make sense, since, while you don’t get the immediate benefit of fat burning created from an energy deficit during exercise, you would still get the additional benefit of an elevated heart rate and metabolism the rest of the day. As long as you don't overeat for the day, you would still experience an energy deficit and thus weight loss.
This study suggests different tactics for different body types and goals.
It suggests that individuals who are concerned only about weight loss, or who have significant body fat to start benefit most from the greater energy deficit gained from not taking in any energy during cardio.
Individuals who are looking to preserve muscle mass while dropping body fat may benefit more from replacing some or all of the energy lost during exercise in the form of protein. A slower rate of fat loss would be offset by preserving muscle mass.
The one clear group for whom no energy replacement is a must were obese or extremely overweight people. For obese subjects, the only way to lower blood lipid profiles post exercise was without replacing energy during exercise.
Reference:
Energy replacement attenuates the effects of prior moderate exercise on postprandial metabolism in overweight/obese men
F L Burton1, D Malkova1, M J Caslake2 and J M R Gill1
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