NAF Slim Pellets. NAF Slim is a natural and highly palatable weight management supplement that provides essential micronutrients to horses on a restricted diet. NAF Slim helps to promote well being for good doers whilst supporting healthy weight loss the natural way. Slim also supports insulin action and normal blood glucose levels in horses and ponies prone to weight gain. NAF Slim should be used in conjunction with a calorie controlled diet and a suitable exercise regime.