From getting glasses for the first time to gaining weight, seeing thinning hair, and — for women — having hot flashes, the 40s can be a time of surprising physical changes.

You may also notice another burst of physical changes that usher in a loss of strength and increased susceptibility to chronic disease in your early 60s. That's the conclusion of a new Stanford University study that found that for many people, aging happens in sudden bursts around age 45 and age 60.

Molecular changes the researchers found around age 45 included those that affect cardiovascular health, skin and muscle condition, how the body metabolizes fats, and how it reacts to alcohol and caffeine.

In the early 60s, the changes observed included those that affect the metabolism of carbohydrates, immune regulation, heart and kidney health, and quality of skin and muscle tissue.

But whether these changes are triggered by unhealthy habits (increased alcohol consumption or declining levels of physical activity) or inherent in your body's physiology, you can do a lot to counter the effects.

A sustained commitment to maintaining muscle tone is of primary importance for dodging these super-aging time zones, according to the researchers.

They also stress that it's important to limit intake of processed carbs and unhealthy trans and saturated fats, and make sure to stay well-hydrated in order to protect kidney function.

For support and guidance, Dr. Mike's book "The Great Age Reboot" outlines just how you can dump the slumps.