Q: mike im a girl and i never really have worked out... i started working out everyday this weekby runinng for about 35 min and the first two days i lost weight but then i started gaining, could it be the muscle weight or is it just ive been eating more?

A: You can't reliably tell whether you are gaining or losing weight in just one week. Your weight naturally fluctuates up and down a couple pounds day-to-day as you eat and drink different foods on different days. Don't worry about day-to-day changes, but instead focus on longer term changes. For example, if first week your weight fluctuates between 137 and 140 pounds but by third week it fluctuates between 133 and 138 pounds, then you know you're losing about one pound per week.