I have consulted several clients over the years, and many come to me saying that although they exercise and have relatively healthy eating habits for the average person, that they are either gaining weight or unable to lose excess pounds despite their best efforts. One of the first things I have these folks look into are ways to improve their "microbiome" or the types and levels of helpful bacteria in their systems.

Chronic stress, antibiotic use, painkiller use and unhealthy diets (refined, processed and fast food rich, to name a few of the problems with the current western eating habits) can all lead to problems in the balance of gut flora, which in turn can lead to weight gain.

Here's a link to a helpful article, which has a second link guiding you on possible ways to heal your gut and possibly lose those stubborn pounds!

http://chriskresser.com/could-a-leaky-gut-be-making-you-fat