Sons weight loss

So almost two weeks ago my son started along with me on this new way of eating and he has not got any of the keto flu at all.. and has not been sick or have headaches or fatigue he is not very much over weight as i am  and he still is losing weight very fast/ he is down I believe he said eight pounds so far which imo for his size is awesome so even if you just need to lose a few this woe works