 Just last week, scientists discovered that a healthy diet at 40 means a healthy life at 70. Now comes a study finding that getting to a healthy 40 isn't a given. So many people in their 20s assume that since they're young, they'll bounce back. Researchers at UC San Francisco found that's not true. They followed about 2,400 people over 18 years, so this is real data, not theory. When you're unhealthy in your 20s, not exercising and smoking, the inflammation in your body causes long-term health consequences.