Can tracking your metabolism help you lose weight?

Promotional feature with Lumen

Cyclists are forever looking to improve their power to weight ratio, but losing weight too quickly or without careful moderation can be detrimental to performance.

Knowing what fuel your body is using during different forms of exercise can help you to feed it more appropriately for your goals, ensuring you've got enough energy in the tank for the next session and helping you to avoid going to sleep on a belly full of food that doesn't complement your goals.

Why does it matter if you're burning carbs or fat?

Food can be split up into three macronutrients: carbohydrate, fat and protein.

Carbohydrate is broken down into glucose for immediate use. Anything left over is converted into glycogen to be stored in the muscles and liver for later use. Converting carbs into energy requires less oxygen than using fat - so it's what the body favours when you're exercising at high intensity (anything over 70 per cent of max heart rate).

At low intensity, your body can use fat quite easily - which is good to know, since even lean athletes have around 100,000 calories worth of fat stored and available for use.

The third macro is protein - but the body only uses this as a fuel when fat and carbs are low, its primary use is the building and repair of muscle.

>>> Fat burning explained

How does the Lumen work?

If you know when your body needs fat and when it needs carbs, you can feed it appropriately. Lumen is a device which athletes can use to manipulate their fueling to help them achieve their goals.

Lumen was founded by twin sisters Michal and Merav Mor. Both have PhDs in Physiology and were training for an Ironman. The device was launched via a successful Indiegogo campaign and has been backed up by an additional study conducted by San Fransisco State University. 

"Lumen provides our users their metabolic state - whether their body is using more fat or carbs for as their metabolic fuel," explains the Lumen VP of product, Tomer Harry.

He went on to explain: "The Lumen measurement in the morning is an indication of the user metabolic health - optimal metabolism means your body usually will be using fat for fuel in the morning. Furthermore Lumen provides our users a metabolic flexibility score (Flex) which is an indication of how efficient is the user shifting between fat and carbs.

"Also Lumen enables the user to track the key factors affecting the metabolic state: macros (emphasising the amount of carbs), physical activity, sleep and fasting. Lumen provides a daily feedback loop between the collected data and the metabolic state so the user can connect his actions to results."

So how do riders put this information into practice?

"Lumen users are encouraged to take a measurement to see if their body is fueled for a workout, and after the workout they can measure the impact of the workout on their body," Harry says. "For example some users were able to see the impact of a cycling workout compared to a HIIT (High Intensity Interval Training) workout and understand how they should fuel the body before the workout."

Lumen can then take this information, and provide a nutrition plan designed to support and optimise training.

Endurance cyclist and triathlete Mike Whincup has been using a Lumen device for just under a year.

"I wanted to try lumen to get a better understanding of my nutrition and training -  establishing that what I was doing was either correct or not, and if not be able to make adjustments," Whinecup says.

"A couple of breaths a day lets me know if I'm in the zone for my goal, whether that be fat burn or fueling for a race. I've been using Lumen for six/seven months and I have lost weight and learned more about my body and how I react to certain foods/fuels."

"Its helped my mentality that some days its best not to train to be optimal and get the best out of your training. Its allowed me to be more fluid with my workout structure," he added.

Whinecup monitors his training via TrainingPeaks, also using a Whoop band alongside logging food on MyFitnessPal. Adding in Lumen was an extra piece of the puzzle.

"These four pillars help me structure my workouts, my recovery, my nutrition and planning when to blend all these elements. It might not be the ideal time to do a hard V02 workout but with these tools it might be more ideal to go for an hour of paddleboarding or an active recovery walk or run," he said.

Advising future users, he added: "My advice to a new lumen user would be to stick with it and make it part of your daily routine. The benefits will be apparent quickly. Forming healthy daily habits such as using lumen as a positive impact and lets you get to your goals quicker and easier."