Chrono nutrition is a holistic approach to eating that considers the impact of meal timings on body's natural circadian rhythms and metabolic patterns. Just like how quantity and quality of food affects one’s well-being, ‘when to eat’ (meal timing) does impact metabolic health and well-being. The body's circadian rhythms are not exactly 24 hours long; instead, they are synchronized by Zeitgebers, which include exposition to light and food consumption.

Unhealthy behaviours like inadequate sleep, skipping breakfast, not consuming largest meal during lunch, calorie dense snack, late night eating followed by late dinner with shorter interval between dinner and sleep (shorter evening latency) negatively affects the metabolic health and circadian rhythm.

In night owls or night shift workers, the melatonin (sleep hormone) levels go down which causes disturbed and unrefreshed sleep which in turn affects the production of appetite hormones thereby increasing risk of obesity, prediabetes, type 2 diabetes, and cardiovascular disease.

In breakfast skippers, low appetite signalling, and higher risk of increasing BMI was observed. The cortisol level increases post 30-60 minutes of awakening. It is better to consume the largest meal during 1-2pm. Studies show that people consume packaged and processed foods rich in sugar, refined carbohydrates, sodium, and unhealthy fat rich foods in the evening. Unhealthy, snacking pattern to be replaced with fruits, home prepared healthy snacks. At night, the melatonin production gradually increases, late and large dinner increases the risk of obesity and associated complications. The quality of sleep decreases with a shorter evening latency. Hence, it is always better to have an early and small, dinner preferably before 7pm.

Practicing mindful eating and having an early, healthy dinner can also help decrease midnight cravings.

The reasons for these unhealthy behaviours stem from lifestyle choices and environmental influences like using artificial lighting during night, constant changes in work timings, and constant access to processed foods. These unhealthy behaviours, unlike genetic factors, can be changed for the better, through lifestyle modifications. It takes only few days to switch over to a healthy dietary pattern and lifestyle.