.” Muscle responds to resistance, so if it’s too light, you won’t see good results. A little bit of pain – or a healthy bit of grunting – is the secret to correct kind of gain here. “You should struggle to eke out those last few reps,” she says
. But that doesn’t mean staying slim is a battle you can’t win. It’s possible to outsmart your genes and maintain a healthy weight.Case in point: a 2009 Finnish study published in the International Journal of Obesity tracked 16 same-sex twin pairs (chosen because
