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Regarding the quantity, it is difficult to give a general recommendation, but following studies speak of at least 5-6 hours per week of physical activity of certain intensity. A pure ectomorph need less (Factory brings accelerated metabolism) and an endomorph more.
Alpha Limit The concept of energy balance is unhelpful for the general population. If we focus on the food and proper motion, is easy to maintain energy balance.
In addition, the level to which the energy balance occurs matter. Eat more and move generates a much more favorable hormonal environment that simply cut calories, both in terms of health and body composition.