I've never had any weight problems (I'm technically underweight according to my BMI) or health problems. I've weighed the same since high school, regardless of what my diet and exercise has been like.
I actually started researching healthy diets/lifestyles after I got my first dog shortly after graduating college: the first creature other than myself I actually had to take care of and be 100% responsible for as an adult. I found out different dog foods were vastly different in quality, and eventually I switched from the holistic/natural kibbles to a raw prey-model diet for my dogs.
During all my research, and finding out how non-species-appropriate the dog food formulas are and how in-bed the vets were with the dog food companies, I started looking at my own diet and wondering if that was wrong too.
I first read books by Michael Pollan and Nina Planck, and was blown away and angered by how misled the American people have been on what constitutes a "healthy diet". I started moving towards the WAPF way of eating. Then I came across the idea of paleo and primal lifestyles, I'm not a big bread person anyway, and it just makes sense and seems like the healthiest option.