People With Two Rare Mitochondrial Disorders Burn About 180 Extra Calories a Day

On a Thursday morning in July 2021, Martin Picard sat in a narrow research room and watched blood leave his arm through a tube that ran through the wall.

Picard, who leads the Mitochondrial Psychobiology Lab at Columbia University Irving Medical Center in New York, had volunteered as his own first test subject. His room held a bed, a metal sink, and a toilet crowded close together. Nurses took blood every hour through the day and night, even after he fell asleep. During waking hours, he also left saliva and answered brief questions about how he felt.

The space resembled a jail cell, or an unusually tight hotel room, but it was built for careful measurement. It belongs to a small global set of about 50 sealed rooms designed to track human metabolism. Because Picard could barely move inside, he could burn only about what his body required to stay alive. Daytime naps were forbidden. Food arrived on a fixed timetable in carefully measured portions. Sleep began at eleven at night, with sensors worn overnight to record his heart, breathing, and brain signals. He passed the idle hours with a book and a computer, and he later described feeling mainly excited.

The lab set out to gauge the fuel needed to keep a person alive at rest, and to compare healthy volunteers with people whose cellular engines are impaired. Picard studies mitochondria, the minute parts of cells that convert food into usable power.

At a research meeting in 2025, Picard's graduate student Evan Shaulson described initial results from a small chamber study of volunteers carrying either of two uncommon disorders of those cell parts. The results are preliminary and remain under review, meaning they have not yet been published or peer reviewed. The patients used roughly 180 additional calories per day, about 15 percent more than healthy controls, including during sleep.

"They have to pay a 180-calorie tax every day of life," Shaulson said, roughly the amount in one slice of pizza. The patients also said they felt more tired and under strain. Samples from their blood contained higher amounts of lactate and related compounds, signs of inefficient energy production that have been linked to anxiety.

Then the researchers tracked participants for nine days in their normal lives. Instead of an intravenous line, volunteers drank water tagged with rare forms of hydrogen and oxygen, and the team estimated calorie use from what appeared later in urine. In ordinary life, the gap between the groups nearly closed.

The activity figures explain why. Healthy volunteers used about 16 percent more energy in ordinary life than inside the sealed room, while patients increased by only about 5 percent. Shaulson said the sealed room routine reflected "a more typical day" for someone with such a disorder, because low energy keeps patients less active.

Picard said the team now plans a larger follow-up involving roughly 100 volunteers and directed by Shaulson. Besides brief time in a chamber, volunteers will wear activity trackers for half a year, check in through a phone program, provide saliva, and describe their day-to-day lives.