All milk from the supermarket is reformulated, none of it is any more natural than the rest, it's just a question of how much fat they put back in when they stick the bits together again.
Weight-wise I highly doubt that it's going to make much difference. the overall balance of diet and lifestyle - ie, active or sedentary - will have a much bigger impact, surely, than whether or not the milk you have has x or y % of fat in it (It's not like it's a big component in overall diet).