High insulin levels negate the positive effect of yohimbine on the A2 receptors, which are predominant in thigh and hip areas of women, and in the abdomen of men.
Taking yohimbine products on an empty stomach is preferable, so timing dosages at least 90 minutes after meals containg carbs, but at least 45 minutes prior to the next meal containing carbs, is ideal. You can also take these products while ingesting protein and/or fat since neither will spike blood insulin levels.
Using yohimbine products while following a low-to-moderate carb/moderate-to-high protein nutritional program (i.e., 0.30 - 0.40 grams/lb of bodyweight of carbs/ 0.60 - 0.80 grams/lb. of bodyweight) should be beneficial provided you are performing some weight training and some aerobics.
Good luck...