Ever wonder why your appetite fluctuates depending on the time of year? A new study has revealed a link between our eating habits and seasonal transition, and it turns out the best season for our metabolic health might surprise you.
If you’re based in a state that recently switched over to daylight savings mode, perhaps you felt a shift in your routine beyond your wake-up time. Speaking to fellow Sydney-siders, I’ve heard a number of claims, each attributing a sudden feeling or disruption to the winding back (or forward, I still never quite know…) of our clocks.
“My whole sleep schedule is disrupted”
“I feel out of whack”
“I’m SO hungry all of a sudden”
And while the latter claim, that the amount of daylight influences our appetites, may seem farfetched, experts may have finally unlocked some scientific evidence supporting the idea. The latest study from the University of Copenhagen explores the effect of light hours on the appetite of lab mice, and the results are likely to take you by surprise.
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Details of the study
Considering most people around the world experience at the very least a two-hour difference in light between the summer and winter months, the team behind this study aimed to explore the impact of daylight deficiency or abundance on our eating habits.
The focus of the study introduces an important distinction, as even though thorough research has been conducted to explore metabolic behaviour in response to exercise and chronic health conditions, all existing studies hypothesise on the assumption that participants will be subject to an equal length of day and night all year round.
“We exposed laboratory mice to different light hours representing different seasons and measured markers of metabolic health and the circadian rhythms of these animals,“ says Lewin Small, a representative from the Novo Nordisk Foundation Center who fronted the study.
What the data revealed
After analysing the behaviour of the mice exposed to either ‘summer light’ or ‘winter light’, researchers concluded that seasonal variation does indeed impact eating habits, indicating a similar pattern of behaviour in humans.
„We found that even in non-seasonal animals, differences in light hours between summer and winter do cause differences in energy metabolism, in this case, body weight, fat mass and liver fat content,“ says Small.
„We found this mostly in mice exposed to winter light hours. These mice had less body weight gain and adiposity,” he adds. “They have more rhythmicity in the way they eat over a 24-hour period, and this then led to benefits in metabolic health.“
While the results gathered from the rodent participants yield strong supporting evidence for the influence of daylight on our appetites, the lack of human data may leave some people sceptical. However, the decision to use mice in the study was fuelled by more than just a desire to stick to budget.
“Mice are not considered seasonal animals, as like humans they do not only breed in specific seasons,” explains Small. “Animals breeding in specific seasons gain weight before the breeding season to save energy supplies.”
The results of the study not only have researchers questioning the impact of seasonal light on our eating habits, but also that of artificial light. Authors of the study are calling for further exploration of the influence our late-night scrolling and binge-watching may be having on our appetites.
“Further studies in humans may find that altering our exposure to artificial light at night or natural light exposure over the year could be used to improve our metabolic health,“ says Juleen Zierath, a senior author of the study and Professor at the Novo Nordisk Center for Basic Metabolism Research.