Timing is everything. Part 1: Nutrition

Meyken Houppermans, PhD. CrossFit Level 3 Trainer.
Founder and Head Coach
Evening types have a higher risk of developing obesity, diabetes type 2 and high cholesterol levels. Timing of meals and living according to your biological clock matters.

Morning or evening type

Our daily lives are structured by a 24-hour time frame. When the sun rises we wake up and start our day. When the sun goes down we end our day and go to bed. At least most of us. Despite this 24-hour rhythm, some people are more energetic and productive in the morning, while others prefer night times. These sleep–wake time preferences can be classified into three chronotypes: The morning type, the intermediate type, and the evening type.

The morning type prefers an early bed time and early morning rise time. The evening type prefers a later bed time and a late morning rise time, and the intermediate type is somewhere in between. Morning and evening types differ genetically, and they have a different lenghts of their circadian rhythm, their internal biological clock. Furthermore, the evening type has a higher risk of developping health diseases such as obesity, diabetes type 2 and high cholesterol.

Circadian rhythms

Circadian rhythms are natural physical, mental and emotional processes in the body in respond to light and dark (day and night). Circadian rhythms are also known as the sleep- wake cycle, or the biological clock. Every tissue and organ in the body has a biological clock, and all clocks are coordinated by a master clock in the brain that receives input from the eyes (light).

Circadian rhythms influence several processes in the body among which hormone release, eating habits, digestion and metabolism. Several factors such as a jet lag, evening shifts at work, blue and artificial light from screens and buildings in the environment, can disrupt circadian rhythms. These disruptions can have health consequences such as an increased risk for sleep disorders, obesity, diabetes type 2 and mental health issues.

Timing of food is relevant

Light is the primary zeitgeber for circadian rhythms. External cues such as the timing and composition of food intake can also affect the biological clocks in the body. The clock- genes thoughout the body influence the timing of digestion, nutrient uptake and metabolism, hormonal regulation, food intake, behavior, and appetite. Therefor, timing and composition of food intake are also important zeitgebers.

Eating at an inappropriate times, for example in the middle of the night; and eating irregular and skipping meals can have a disruptive effects on circadian rhythms. This circadian misalignment (wakefulness and food intake when the internal circadian system is promoting sleep) can lead to increased risk of obesity, diabetes type 2, hypertension and high cholesterol.

Evening types have higher health risks

Evening types consume most of their calories closer to the time when the body is ready for sleep and melatonin levels are high. Eating later during the day is associated with increased risk of obesity, diabetes type 2, high cholesterol levels and high cortisol levels (the stress hormone).

Evening types, as well as people with a disrupted circadian rhythm for example due to working night shifts, seem to make unhealthier food choices compared to morning types and people with a regular schedule.

Research shows evening types often skip breakfast and lack energy in the morning. Later during the day they comsume larger portions compared to morning types; more often take a second serving; and eat more calories in the evening. Emotional eating, stress eating and cravings are more prevalent among evening types. They have less control over their diet and over the amount of food intake. Furthermore, the diet of evening types contains less healthy products such as fruit, vegetables, wholegrain products and lean protein; more unhealthy processed and high carb foods; and less vitamins and minerals, compasred to the diet of morning types.[1]

Find your rhythm

A calendar day takes exactly 24 hours, but circadian rhythm takes 24,2 hours. Ideally, for health reasons, both are aligned as much as possible by living according the natural rhythm of day and night. Being a morning type of evening is a natural predisposition and relevant to take into account, for example to plan difficult or challenging activities at the times when you have the most energy. Regardless of chronotype, extremes should be avoided, such as waking up in the middle of the night to eat.

Some tips:

1. Eat at set times

Try to eat at set times during the day with at least three hours between every meal. Grazing all day messes up our biological clock. Stop eating 2,5 hours before bed.

2. Adjust to your chronotype

Adjust your meals to your natural rhythm: if you are a morning person you might need more energy in the morning by eating a proper breakfast. If you are an evening person, you might need a bit more energy during the day, with a smaller breakfast but a proper lunch. In any case, eating a heavy meal at the end of the day is not preferred, since our metabolism doesn’t operate as optimally.

That same applies to work and exercise (Timing is everything in exercise): Plan work that requires full focus during your best hours of the day, and plan your exercise sessions when you have energy. This increases your chance of success at work and at the gym, and helps to stay healthy.[2]

Create your own health!©



Chaput JP, McHill AW, Cox RC, Broussard JL, Dutil C, da Costa BGG, Sampasa-Kanyinga H, Wright KP Jr. The role of insufficient sleep and circadian misalignment in obesity. Nat Rev Endocrinol. 2023 Feb;19(2):82-97. doi: 10.1038/s41574-022-00747-7. Epub 2022 Oct 24. PMID: 36280789; PMCID: PMC9590398.; National Institute of General Medical Sciences. Circadian Rhythms. Retrieved 2020.; Van der Merwe C, Münch M, Kruger R. Chronotype Differences in Body Composition, Dietary Intake and Eating Behavior Outcomes: A Scoping Systematic Review. Adv Nutr. 2022 Dec 22;13(6):2357-2405. doi: 10.1093/advances/nmac093. PMID: 36041181; PMCID: PMC9776742.

[2] Wageningen University; Meléndez-Fernández OH, Liu JA, Nelson RJ. Circadian Rhythms Disrupted by Light at Night and Mistimed Food Intake Alter Hormonal Rhythms and Metabolism. Int J Mol Sci. 2023 Feb 8;24(4):3392. doi: 10.3390/ijms24043392. PMID: 36834801; PMCID: PMC9963929.; Montaruli A, Castelli L, Mulè A, Scurati R, Esposito F, Galasso L, Roveda E. Biological Rhythm and Chronotype: New Perspectives in Health. Biomolecules. 2021 Mar 24;11(4):487. doi: 10.3390/biom11040487. PMID: 33804974; PMCID: PMC8063933.