Hubby's diet

So Hubby has been on this new diet for over a week now, but realized he's started gaining weight. He was feeling discouraged and thinking of not following the diet as was given to him, but after I talked to my brother (who gave us the diet and has used it successfully) we realized what the problem was- Hubby wasn't burning as many calories as he's been eating because the new diet is higher in fat than how he used to eat. So for now we aren't resorting to him using hydroxy cut or something, he's just going to watch his calories better and exercise more. The only other problem is that all the exercising he's been doing has started giving him shin splints, so he needs to work on doing things with lower impact on his legs until they are better.