The future of nutrition is... not what you expect. Sure, we've got epigenetics, and personalised nutrition and that's great and all. But, you know that old saying; breakfast like a king, lunch like a prince, dinner like a pauper?
Well, now we have the science to back that shit up.
It's called chrononutrition: call your gran, she was right the whole time.
What I see in practice is basically the inverse of this proverbial wisdom; weak b'fast and lunch, mahoosive dinner, and evening snacking. This pattern of restricting and bingeing does you a massive disservice. Here's why.
All life is dictated by daily cycles. The name used in biology is circadian rhythm, and it rules just about everything, including your metabolism. When there's a disconnect between your metabolic rate and the food you're eating, it causes circadian misalignment.
Every organ and system in our body is controlled by special genes called clock genes (real cute, scientists). You've heard of your 'body clock', yes? That's' what I'm talking about. These clock genes help us maintain our circadian rhythm through complex feedback loops, that in turn, programme and regulate other genes.
There are clock genes for sleep and wake cycles, for your core body temperature, and for melatonin production (that sleepy time hormone). Then there are clock genes for metabolising sugar and fat, for digestion, for the immune system and yes, even for pooping.
You know what happens when you forget to move your clocks forward, or your phone dies and you don't know the time? It's a shit show, right? You're confused, you're late for stuff, you miss appointments. It's a mess. Same thing happens when your clock genes are desynchronised. Some scientists believe that this could lead to metabolic disorders, weight gain, diabetes, cardiovascular disease, cancer, and even psychiatric disorders.
Why? Well, put simply, when things happen at the same time every day, it saves the body time and energy. This would have given us an evolutionary advantage (probably). The theory is, that "[the] ability of organisms to temporally regulate diverse biological functions enables them to maximize their ability to cope with and anticipate predictable 24-hour changes in the environment."
So, basically what I said.
Your circadian rhythm can get knocked out of whack when you don't eat at consistent times. Ditto when you skip breakfast and eat late at night. Researchers say it's similar to being jet lagged or doing shift work, your body is all kinds of confused. And this can lead to metabolic issues, like insulin resistance and high blood sugar levels.
It's pretty well established that populations who eat breakfast, have a lower BMI, and that skipping breakfast increases the odds of being overweight or obese. Night eating syndrome (where there is a time delayed eating pattern) is positively associated with BMI. Researchers believe that eating late and skipping b'fast leads to weight gain and obesity. One reason for this may be an insufficient satiety function. Clock genes control the satiety (or fullness) hormone, leptin, and circadian misalignment causes a reduction of leptin in the blood stream throughout the day.
But that's not the whole story; dietary induced thermogenesis (DIT) is the name given to the rise in body temperature after eating a meal and is one aspect of what we commonly call metabolism. We have to spend energy in order to digest, absorb, and assimilate the food we've just eaten, and this causes our body temp to go up. We know that DIT is under circadian control, so it's highest in the morning, and tapers off throughout the day. You can think of this as your metabolism being higher in the morning and dropping off later in the day. Scientist hypothesise that this could (at least in part) account for why people who skip b'fast don't necessarily lose weight (especially if they eat more later in the day when their metabolism is slower).
But it's not just the timing of food that's important here; the types of foods and nutrients consumed also influences circadian clocks and how strong their signal to the rest of the body is.
Caffeine, from tea, coffee, cola, and chocolate (everyone conveniently forgets about chocolate), prolongs circadian activity, and is thought to affect a fundamental part of the circadian system. Researchers have shown that a cup of coffee three hours before bedtime, can set the clock back by around 40 minutes, delaying melatonin production (that sleepy time hormone), and causing disruption in the synchronisation of your clock genes.
That same study found that exposure to bright light at bed time can cause a phase delay (think of it as setting your clock back) of 85 minutes, and if you do both coffee and bright light, it's about 105 minutes. Most people think about the light coming from their computer/TV/iPads/phones, but even the 'big' light in your room could be influencing how easy it is to fall asleep. Think about turning off the big light when it starts to get dark, and use lamps and dimmers instead. Equally, exposure to daylight helps entrain the clock genes during the day, so they stay synchronised.
Another cool study found that when people don't sleep enough they tend to eat more, and observational studies have noted a link between sleep deprivation and energy intake. In other words, you get hangry when you sleepy.
High fat, high salt, and high GI/GL diets, can also cause unwanted shifts in circadian rhythm, although lots more research needs to be done to figure out exactly how these things work, it's a good idea to follow dietary advice to minimise added fats and oils, salt, and to eat wholegrains, starchy vegetables, and beans, which are low GI.