A recent Danish study shows that people with thighs less than 24 inches around face a higher risk of heart disease and premature death, even if their body mass index (BMI) is normal. Not only do model-skinny thighs mean less muscle mass (which may mean the body is less able to regulate insulin levels), but some scientists hypothesize that thigh fat acts as a "metabolic sink," flushing the blood of harmful triglycerides (which raise your risk of cardiovascular ills).
Depending on your age and your health, some blood screenings make a lot of sense, while others can be put off until you're older. We spoke to a number of experts to come up with the right protocol for your 20s, 30s, 40s, and beyond.