What’s next for the business of longevity?

But living longer would still probably mean working longer. “The one thing that I don’t think is going to happen is that we will be able to retire at the same age,” Dr. Sinclair said.

We are on the “first flight stage” of the research into longevity, according to Dr. Sinclair. Critics of longevity research argue that the billions investors have put toward longevity are focused on enriching only the wealthy, and that the money would be better spent on more immediate issues. Dr. Sinclair, though, compared research into longevity to initial work in industries like air travel, which was originally funded by and offered primarily to the wealthy. “The people who invest in that are the rich — they have to be,” Dr. Sinclair said of longevity research. “This is the way capitalism works and it’s worked well.”

His goal, he says, is to “democratize” longevity drugs, education and knowledge. As for an academic’s role in the business of longevity, he said, “it is now at Harvard Medical School unusual for a scientist not to be involved in industry somehow and there are plenty of entrepreneurs around me.”

Dr. Sinclair’s personal regimen is a “combination of eating right, living right, exercising,” as well as some supplements and the drug metformin. Metformin is a diabetes drug that some people without the disease have begun to take in hopes of staying healthier longer. Some studies, though, have suggested it may also blunt the health benefits of exercise.

He is also a fan of intermittent fasting, which he said has helped improve the life span of mice. I’ve been skipping breakfast my whole life and lately, over the last two years, I’ve been skipping lunch,” he said.

Limiting food intake to certain hours of the day has gained popularity over the past few years. Advocates of the dietary regimen argue that it forces the body to break down fat for energy, once glucose has been depleted. When that happens, the body can go into a state of ketosis that can be similarly achieved by low-carbohydrate diets, whose proponents say have benefits ranging from burning more calories to managing diabetes. (Ketosis also has risks, like liver damage.) Research into intermittent fasting is still evolving. A rigorous three-month study published in September found that people experimenting with the diet lost little weight, and much of that may have been from muscle.