Diet, exercise and sleep are the three most important factors when it comes to supporting your immune system. A diet that’s high in (processed) carbs fuels inflammatory processes that your immune system has to fight. As a result, your body has fewer resources to fight acute infections, such as viral infections. The fitter and better-working your metabolism is, the more resources your immune system has to do its job. Since I started with a ketogenic paleo diet and intermittent fasting a few years ago, I have not gotten sick.  I know that’s anecdotal evidence, but I also know that I used to get sick a lot before and now I don’t. Something has changed, and I like to think my lifestyle has something to do with it.