Cedars-Sinai Blog

Q&A: Metabolism

metabolism, weight loss, health, food, eating, energy

Metabolism is the process of converting food into work energy or stored energy.

"As you get older, if you follow the same diet you always have, your body will store more fuel as fat."

To help us understand metabolism, we spoke with Dr. Roberta Gottlieb, director of Molecular Cardiobiology, who studies metabolic processes and their effects on the body at the Cedars-Sinai Gottlieb Laboratory.

What exactly is metabolism?

What's work energy?

If ATP handles the work energy, then how does the body store energy?

People often claim they have a slow metabolism. Is it a real thing?

Dr. Gottlieb: Yes, it can be true. Slow metabolism is when our energy needs decrease, and the body gets more attuned to storing fats—this happens especially as we age.

Is that why it's so hard to lose weight as you get older?

Dr. Gottlieb: Well, the body gets really good at storing energy as we age, and storing energy as fat is really efficient.

So, as you get older, you require fewer calories to meet your daily needs—partly because we get less active and our muscle mass decreases, so there's less muscle tissue burning ATP.

A 20-year-old might require about 2,000 calories a day, whereas for women after menopause or men in their 60s, daily calorie needs drop below 1,500 and sometimes below 1,200 calories.

As you get older, if you follow the same diet you always have, your body will store more of that fuel as fat.

Is there any scientific evidence that certain diets, such as eating 6 smaller meals a day, help speed up metabolism?

Dr. Gottlieb: If you start eating at 7 am and you keep eating until 11 at night—even 6 smaller meals—you'll never give your body the chance to tap into its energy reserves.

What I do think is metabolically beneficial is the concept of intermittent fasting.

What's intermittent fasting?