Struggling to lose weight despite eating well and exercising? Biochemist Dr Sara Pugh joins Liz to explain why the answer may not just lie in what’s on your plate – but in how much natural daylight you’re getting.
They discuss how leptin, the appetite-regulating hormone, follows our circadian rhythm and the link between light exposure, sleep and satiety.
Sara also talks about the effects of screen time and artificial light on metabolism and shares ways to reconnect your body with natural light cues.
Stream the episode below, or download the recording via Apple Podcasts or Spotify.
4 ways to optimise light exposure for a healthier metabolism
When we think about maintaining a healthy weight, we tend to focus on nutrition, exercise and sleep. But Dr Sara Pugh believes another essential ingredient is often overlooked: natural light.
“Our bodies evolved to respond to daylight,” she explains. Natural light helps regulate our circadian rhythm – our internal body clock – which influences everything from energy levels and mood to the hormones involved in weight management.
Here she shares four ways to reconnect your body with natural light cues and help support a healthy metabolism.
Make the most of mornings
Early-morning light helps signal the production of dopamine and serotonin, while setting the stage for melatonin production later that evening. It’s also an important time of day when it comes to activating leptin, Sara explains.
One of the body’s key metabolic hormones, leptin helps regulate our appetite and energy levels. Rather than simply responding to food intake, it also follows our circadian rhythm and is very much influenced by light exposure.
“If we have bright light during the day and darkness after sunset, that’s a huge factor in helping leptin signalling,” says Sara. Catching the sunrise provides the most optimum light benefits, but getting outside within an hour of waking will help align your body to its natural circadian rhythm, even on a cloudy day.
Activate evening fat-burning
While we need bright light during the day, darkness at night is also important for healthy leptin signalling and melatonin production, says Sara.
Morning light sends a signal to our internal body clock to start producing melatonin, the sleep hormone, as evening sets in. But as well as supporting better sleep and overnight repair, melatonin is an important metabolic coordinator.
“Melatonin is very important for fat burning during the night,” explains Sara, but exposure to too much bright light in the evening will delay its release. She recommends reducing bright lighting and screen use after sunset and keeping your bedroom as dark as possible by removing devices and using blackout curtains.
Eat with the light
When you eat can be just as important as what you eat, highlights Sara, explaining how we evolved to eat our meals between sunrise and sunset. “We’re meant to eat when there’s light and stop when it’s dark,” she says.
Busy work schedules have made us fall into the habit of eating our evening meal far too close to bedtime and snacking late at night, which interrupts leptin signalling. Start the day right by eating breakfast within an hour of waking to help set the natural body clock and keep your appetite regulated.
Take regular light breaks
To get the most metabolism-boosting benefits, gradually increase exposure to natural light throughout the day, particularly in the morning. Find ways to incorporate regular daylight into your routine by taking the dog for a walk or having your lunch break outdoors.
What’s important is allowing skin to safely adapt, emphasises Sara. That means preparing the skin with gradual exposure, seeking shade when the sun is at its strongest and taking care not to burn.
She recommends wearing a hat if facial ageing is a concern, while allowing other areas of skin to benefit from daylight where appropriate.
“Start small, taking light breaks where you can,” says Sara. Even just opening a window, stepping outside for your morning coffee or taking a short walk before work can help your body align with its natural circadian rhythm.
Also in this episode:
- The importance of early-morning daylight for mood and metabolism
- Why artificial lighting after dark disrupts fat-burning
- How light exposure regulates our hunger hormones
- The surprising impact of late-night scrolling on your weight
- Why eating within daylight hours keeps hunger signals balanced
More from Sara:
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