Merav and Michal Mor do almost everything together.
The identical twins studied at the same university, both pursuing PhDs in physiology on heart health, each with a slightly different focus. For fun, they even decided to start competing in triathlons together.
Both became fascinated with understanding metabolism to fuel peak performance. They worked together to cofound healthtech company Lumen that tracks metabolism with a signature device that analyzes when the body is burning carbs or fat.
That’s when their lives diverged. The Mor twins still spend time together managing their company, often finishing each other’s sentences. But the two take very different approaches to managing their metabolic health.
It goes to show how personalized nutrition and exercise science can be, even for people who share the same DNA.
Michal said that there’s no one-size-fits-all approach to metabolism, even for a single person, since context matters — what you eat, when you eat, and how much you exercise.
By studying data from thousands of users and their own personal experiences, the Mor sisters have key insights to help more people understand metabolism and burn fat efficiently.
Why metabolism matters
The Mor twins started their intensive triathlon training while completing their doctoral degrees. “We just woke up one day and said, ‘We feel like doing something challenging and extreme,'” Michal said.
They quickly realized that the right fuel was key to balancing both their schoolwork and their training, ensuring peak performance.
“We started to investigate what determines an amazing athlete that will finish the competition with a smile and with an amazing result versus an athlete that will feel sluggish and will not even finish the competition,” Merav said. “The answer was very clear.”
“It’s rooted in our metabolism, and how efficient our metabolism, which is basically our body engine, can switch between burning fat and burning carbs,” she continued.
Courtesy of Michal and Merav Mor
Your metabolism includes all the chemical processes your body uses to produce, store, and regulate energy. A healthy, metabolically flexible body can switch between carbohydrates and fat for fuel, helping support consistent energy levels without major fluctuations in blood sugar.
Lumen measures whether the body is burning carbs or fat for energy using a portable breath test, rather than the complex lab testing typically required. It’s available online, along with a coaching program, for $200 to $600, depending on the subscription length.
Understanding metabolism can help optimize performance for both everyday athletes and elite competitors. It may also support energy levels, support weight management, improve focus, and help control cravings.
And because metabolic health is linked to conditions such as type 2 diabetes and heart disease, it can also play an important role in long-term health and healthy aging.
Prioritize building muscle
A crucial component of the sisters’ performance training is building muscle, a metabolically active tissue that also provides strength and stability.
Muscle is metabolically expensive, meaning it takes up a lot of energy, but it also has the capacity to store and produce energy.
“We did a lot of weightlifting to make our muscles bigger,” Merav said. “So when we have an overload of carbs before the competition, we will have a lot of space to put all that pasta in.”
When you eat a carb-rich meal, they’re broken down into glucose. Some is immediately used for energy, but anything you don’t expend can be stored as glycogen in the muscle tissue and the liver. Glycogen storage helps prevent blood sugar spikes and drops, so you have steadier energy between meals.
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That’s why muscle mass is crucial not only for athletic endeavors but also for longevity, helping reduce the risk of illnesses and prevent injury as we age.
Carb load before a workout
While metabolism can be highly individualized, Michal and Merav have analyzed data from thousands of its more than 300,000 Lumen users worldwide and noticed a trend.
Eating carbs early in the day, or close to a workout, is linked to better metabolic flexibility, or the ability to switch between burning carbs and fat smoothly. That’s important for weight management, since burning fat can help improve your body composition, or ratio of fat to muscle.
“When we eat most of our carbs around a workout, and in the first half of the day, this is also helping our body to shift more efficiently into fat burning,” Merav said.
Metabolism is also essential for performance, since your ability to shift between burning carbs and fat helps maintain steady energy.
Michal uses Lumen to analyze her breath, see whether she’s burning fat or carbs before her morning workout, and understand how to fuel properly. If she’s burning fat, that’s a sign to eat a pre-workout snack like a banana to ensure she has plenty of energy for high-intensity exercise and to support her recovery.
“Based on what is happening in my body, Lumen is giving me a recommendation of how much I should eat in order to best support the workout,” she said. “The shift to carbs means that now I am in the anabolic window, so my muscles are hungry and I should feed them.”
Eat dinner early
The Mor sisters have published extensive research in peer-reviewed journals, such as the Journal of the International Society of Sports Nutrition, on what works for real Lumen users to support a healthy metabolism.
One of the most effective changes is simple: eating an early dinner can help the body burn fat and maintain stable blood sugar.
Courtesy of Michal and Merav Mor
“Early dinner helps our bodies to align our circadian rhythm, our internal body clock. And when our internal body clock is in sync, it gives our mitochondria the ability to repair and rest during the night. And then when we wake up in the morning, our metabolism is able to burn fat very efficiently,” Merav said.
Previous research suggests that late-night eating can disrupt sleep, influence metabolic health, and affect the body’s natural processes of digestion and repair. As a result, some doctors and longevity researchers recommend not eating before bed. Still, there’s limited evidence that eating early alone dramatically changes the body’s ability to burn fat overnight.
Either way, Merav’s personal experience is proof that there are exceptions to every rule. For her, enjoying a late-night pizza with her three kids is worth the tradeoff. “It’s not healthy, but it’s very fun, and I want to have pizza with my kids,” Merav said.
To stay on track, she waits an hour or so after waking to have breakfast, giving her body more time to rely on stored fat for energy.
It’s a good reminder that the best routine doesn’t have to be the most strictly optimized: leaving room for fun and socializing is a key part of long-term health, too.
