Sometimes, making healthier food choices is hard and can require seemingly unsustainable willpower. But what if you could improve your diet without changing what you eat - what if we told you that simply changing when you eat could profoundly affect your health and performance?
The good news is that the emerging science of chrononutrition shows that this is often the case.
Chrononutrition is the relationship between your nutrition and your body’s “clock”. This clock programmes daily roughly 24-hour cycles in all sorts of processes in your body, including your sleep/wake cycle, digestion, metabolism and immune function.
Chrononutrition has several important implications for health and performance:
- What and when you eat influence the function of your body’s clock.
- Your body’s clock optimises your metabolism in particular for specific processes at certain times of day, so you can adjust your diet to improve your responses to the foods and drinks you consume.
- If you have a disrupted pattern of life that puts pressure on your body’s clock, you can use diet to help minimise the negative effects on your short and long term health.
With a background in helping people perform at their best, around the clock, in the most challenging environments on the planet our goal is to help you apply the science of chrononutrition to your daily routine.
KEY TENETS OF CHRONONUTRITION
1. Wait until at least 30 minutes after your natural wake time before consuming anything other than water
If you wake to an alarm, it’s still your biological night-time – a time when your body is not optimised to effectively digest and metabolise food and drink.
2. Eat less, more frequently, consistently
While eating frequency doesn’t seem to have a strong bearing on bodyweight, having distinct 3-6-hour periods between meals (and snacks, if you have them) makes sense for multiple reasons.
One of these is that more regular meal patterns are good for cardiometabolic health.
Another is that if you want to support your muscle mass, it’s best to wait (about 4 hours seems ideal) between consuming boluses of protein. This is because after you saturate your muscles with amino acids from a protein-rich meal, your muscle-building machinery temporarily becomes relatively unresponsive to any additional amino acids.
3. Control your habitual caffeine intake
Judicious use of caffeine enhances mental and physical performance, both when well rested and after sleep loss.
In general, while lower doses (about 1-4 mg caffeine per kg bodyweight) improve cognition, slightly higher doses (3-6 mg per kg) are better for exercise performance. So, while we recommend regularly consuming only up to 3 mg caffeine per kg bodyweight, there’s definitely a time and a place for higher doses.
So, how much caffeine is in commonly-consumed foods and drinks?
The amount of caffeine in items such as coffee and tea is quite variable. Using coffee as an example, a cup of instant coffee typically has about 60 mg caffeine, an Americano often has about 150 mg caffeine, and certain large store-bought coffees contain over 300 mg caffeine.
For a useful database of the caffeine content of various foods and drinks, check out Caffeine Informer.
4. Stop consuming alcohol at least 3 hours before bedtime
Alcohol is toxic in large quantities, and it’s debatable whether any amount of alcohol is good for health.
However, we don't want to throw a massive downer on and tell you not to drink, as occasionally drinking moderate amounts of alcohol can be perfectly healthy for lots of people.
Current UK guidelines suggest that adults consume up to 14 units a week (that’s about 7 pints of beer or 7 medium glasses of wine), spread evenly over 3 or more days.
If and when you do drink, it’s better to drink relatively early. Contrary to hearsay, alcohol is not an effective sleep aid and consistently disrupts sleep late in the sleep period. What’s more, alcohol consumption disposes people to developing sleep apnoea, a sleep-related breathing disorder that increases risk of diseases such as diabetes.
5. Stop consuming any calorie-containing items at least 2 hours before bedtime
About 2 hours before the time you usually fall asleep, the pineal gland in
your brain starts synthesising substantial quantities of a hormone named melatonin. This hormone weakly promotes sleep and acts on receptors in cells in many tissues to signal that it is night-time and hence to engage in night-time processes. Digesting and metabolising nutrients isn’t really one of these processes. Your body is therefore optimised for fasting from about 2 hours before bed until about your natural wake time. So, it’s no surprise that consuming lots of calories late in the day tends to make sleep less restorative.
6. Use a 6-12 hour eating window (caloric period) each day
We define time-restricted eating (TRE) as limiting intake of all calorie-containing items to a period of 12 hours or less each day. We mentioned earlier that the timing of our diets may affect our bodies’ clocks, and it seems that TRE may be beneficial in part by enhancing the function of these clocks.
In the last few years there’s been a flurry of research into TRE. While the research on TRE is preliminary, TRE has been shown to produce numerous cardiometabolic health benefits, including reduced blood pressure, bodyweight, and fat mass, and improved blood sugar control. Interestingly, setting the caloric period as early as is practical in the waking day may be most beneficial. One thing to note here is that we tend to consume different things at different times of day – not many people have wine at breakfast or cereal at dinner! This is one reason that an early caloric period is ideal.
Results from studies of “early” TRE, such as this study, have been particularly impressive, so including breakfast and having an early dinner is likely optimal for many people...provided that it’s feasible in the context of family, work, and social commitments. When having an early dinner isn’t practical, keep your dinner relatively low in carbs and fats.
7. Distribute your protein intake relatively evenly between meals
Changes in your muscle mass depend on the balance between the synthesis
of new proteins and breakdown of existing proteins in your muscles. Each time you consume a sufficient amount of a high-quality protein, you tip this balance in favour of accumulating muscle tissue. As described above, you then need
to wait a few hours before the protein you eat can have a similar effect. This means that if you consume large quantities of protein infrequently (let’s say every 8 hours) or small quantities of protein very frequently (let’s say every hour), you won’t stimulate the synthesis of new proteins in your muscles as effectively as if you eat moderate amounts of protein at an intermediate interval.
So, if you want to support your muscle mass, a dose of about 0.4 g protein per kg bodyweight at each meal (or snack) within your caloric period is generally about right.
8. Consider bouts of strenuous exercise too
While in the absence of exercise it’s best to front-load your calorie intake, strenuous exercise positively affects how your body disposes of nutrients such as carbs.
So, if you exercise hard in the afternoon, don’t be afraid to consume a substantial proportion of your daily carb and fat intake around the exercise.
9. Front-load your carb and fat intake on days when you’re not exercising hard or are exercising hard in the morning
Some fascinating research on overweight and obese women on weight loss diets has shown the advantages of front-loading daily calorie intake.
In one study, one group of women consumed half of their calories at breakfast for 12 weeks (the big-breakfast group). Another group consumed half of their calories at dinner. Even though the quantities of calories, carbs, fats, and proteins consumed by the groups diets was equivalent, after 12 weeks the big- breakfast group lost more than twice as much weight, more than twice as many inches off their waists, and had greater improvements in blood sugar regulation and blood lipids.
So, there really is merit to the old adage of eating breakfast like a king, lunch like a prince, and dinner like a pauper!
10. Consume carb-rich foods at the end of meals and snacks, when practical
Multiple studies have shown that when adults who have prediabetes or diabetes eat carb-rich items 10-15 minutes after they eat fat-, fibre-, and protein-rich items at meals, they have dramatically better blood sugar responses to meals than when they consume the carb-rich items first.
So, when practical, go for fat-, fibre-, and protein-rich items first at meals. Some cultures begin meals with a salad, which is a good idea!
11. Maintain regular diet, supplementation, and medication timing from day to day, when possible
When adults consume a fixed number of meals each day, they have better appetite regulation, improved blood sugar control, and burn more calories than when they consume a varying number of meals – even when the composition of the diets is identical. What’s more, there’s some evidence that when people use a fixed TRE caloric period their sleep also becomes more restorative.
It’s also clear that there is a best time of day at which to take certain medications, for your body’s clock influences how you absorb drugs, distribute them in your body, metabolise them, and excrete them. This means that you may be able to use lower doses of medications and reduce any side effects if you take them at the right time. The same is likely true of many supplements.
If you’re taking medication or get prescribed one, ask your healthcare practitioner for more info about this.
12. Intermittent fasting has its place
Some people use TRE and intermittent fasting synonymously. We don’t, instead, we think of intermittent fasting as periodic use of a fast of at least 24 hours for example, doing one 24 hour fast each week.Intermittent fasting is useful in several scenarios. These include:
- As a tool to remind people what true hunger feels like – many people have been eating round the clock for years, and a 24 hour fast at the onset of a fat loss diet can be a handy teaching tool.
- As a way to shed fat. Intermittent fasting is especially helpful for people who have a lot of fat to lose, for these people generally lose little fat-free mass during fasting and can fast for longer than lean people. How’s this for an epic fast: Beginning in 1965, a 207-kg man fasted for 382 days straight, losing 125 kg!
- To help people during certain transitions. While this hasn’t been rigorously studied, fasting may help you get over jetlag.
- To speed entry into ketosis. At the onset of a ketogenic diet, an extensive fast can help people enter ketosis faster.
- As an adjunct treatment for certain disorders. These include cardiometabolic diseases, some cancers, and certain neurodegenerative disorders.
While purists may use fasts in which people consume no calories (only water, for example), others use “modified” fasting, which typically entails consuming only about 20-25% of the number of daily calories needed to maintain bodyweight.
If you want to try intermittent fasting, perhaps begin with one 24 hour fast every seven days. You can then increase the frequency and/or the duration of the fast.
If you want to try a modified fast, our favourite strategy is a “protein-sparing” modified fast, which will help you hold onto your fat-free mass while still shedding fat rapidly. To use this approach, only consume lean sources of protein (perhaps 1.2 g protein per kg bodyweight per day, evenly divided into 2-3 “meals”), plus small amounts of non-starchy, low-calorie vegetables, such as leafy greens. Like regular fasting, use modified fasting intermittently.
13. Shift workers may benefit from a small snack during shifts
If you’re a shift worker, try a TRE approach and confine your caloric period to when it feels like it’s usually your “subjective” daytime (meaning that time of day when you think you feel most alert on most days).
Then, if you get ravenous outside of this time (during a night shift, for example), choose a small, easy-to-digest, protein- and fibre-rich snack. A small snack is likely to ward off hunger and support your workplace performance.
If you found this article useful, you can get a free copy of our ebook the Principles of Resilient Nutrition here and if you would like help working out you own personal strategy we offer a personal assessment and planning service here.