The biggest difference I've noticed in my general level of health was when I cut out all refined sugars from my diet. It was a difficult thing to do, but was well worth it.
When I say all forms of refined sugar, I mean all forms. Sugar, corn syrup, brown rice syrup, etc, etc. There are a lot of names for sugar, and lately a lot of "health food" items have been sneaking in sugar by calling it something else.
Read all labels carefully. Avoid anything that is not sweetened exclusively by fruit. Once you do this, you'll find that 80% of food at the grocery store (yes, even health food stores) is out of the question. You'll be forced to eat things like fresh fruits and vegetables, and only the best breads.
Obviously soda is out of the question. Turns out the thing I liked about soda was the bubbles. Sparkling water with a hint of lemon is a great replacement. I still drink lots of coffee. Instead of sweetening it with sugar, I just add some cream. After a while, you start to develop a higher sensitivity to the naturally occurring sugars in cream.
It's easiest to make this switch in the summer when there is a lot of access to fruit. I first tried in the winter and only lasted a week. I tried again that summer and have been 100% sugar-free for 3+ years. The only thing I changed about my diet was the simple rule of no refined sugar, and my weight dropped 30 pounds over the course of the next year, and I stopped getting drowsy during the day.
If there is any single change in diet I recommend, it's cutting out all refined sugars. It's not easy but it's worth it.
This was originally posted as comment on an "Ask HackerNews" thread. You can see the original and others' comments here: Ask HN: Have you hacked your nutrition?
