I remember back when I first started getting into fitness and nutrition nutrient timing was all the rage. Everyone had their gym bags stocked with protein powders and shaker bottles and quick digesting carbohydrates to consume the second workouts were finished. We ate a great breakfast and would never, ever even think of eating carbs after 6pm! So what is this all about? Is nutrient timing important? If it is, is it important for everyone? Read on my friends!
Nutrient timing is the application of eating certain foods at certain times in order to achieve certain body composition or health goals. The practice is based on the belief that our bodies can better tolerate or handle different types of foods (mainly carbohydrates and proteins) at different times.
When it comes to nutrient timing, there are a few principles we hear most often:
It is best to consume carbohydrates and protein within 60 minutes post workout.
High carbohydrate intake should be avoided at night (although there are also new suggestions out saying carbohydrate intake should be low in the morning and higher towards the end of the day - more on this later).
Meals should be small and spaced frequently throughout the day.
Proteins, Carbs, and the Anabolic Window of Opportunity
The Old: It used to be believed that we had a short period of time post-workout when our bodies were primed to accept nutrients. We just spent the last hour depleting our glycogen stores and breaking down our muscles and now our bodies are hungry to replace what we just lost. This time period, a window of 45-60 minutes post-workout, is known as the anabolic window of opportunity, a limited time that exists after exercising to optimize training-related body composition adaptations.
This window has been believed to be important for people in two camps. The first, those looking to build muscle: In order to repair and initiate growth of muscles that breakdown during a workout and to restore glycogen stores to improve performance and recovery, protein and carbohydrates must be available to the body as soon as possible.
The second, those looking to lose body fat: Since the body has a better response to carbohydrates post exercise (exercise can help reduce the blood glucose response after consuming carbohydrates), those looking to lose weight would to best do consume the bulk of their daily carbs only post workout and within the window of opportunity.
The new: Even though we, and many of our favorite fitness gurus, used to live by these rules, we don't any more (and neither do they). The research just doesn't support these claims. Instead, here is what we do know: Unless you are training multiple times per day, there is no need to immediately replenish*. Carbohydrate stores will replenish regardless of when you take in them in as long as you are taking in enough, the same goes for eating protein and building muscle. What is more important is total amount of nutrients you bring in daily and the quality of those nutrients.
*There is some evidence to suggest that eating post workout may actually hinder your fitness goals if those goals are to build muscle. This is because after strenuous exercise our testosterone levels are elevated and when we eat carbohydrates post workout testosterone levels fall. While fasting after a workout to take advantage of elevated testosterone levels may be a benefit to men, it may not be to women, especially if it happens consistently. If you are a women and have issues with acne, male pattern hair growth, PCOS, or infertility, you want to avoid fasting post exercise and replenish with quality carbohydrate sources even if following a low carb diet.
Carbohydrates Should Be Avoided At Night (or In the Morning)
It used to be believed that carbohydrates should be avoided at night because we wouldn't be moving around enough to "burn them off" or to reduce your glucose response causing you to either prevent weight loss or even gain weight. Now some suggest avoiding carbs in the morning and instead getting your daily carbohydrate needs in the evening (known as carb backloading). This theory suggests that since insulin sensitivity is higher earlier in the day which allows for greater carbohydrate absorption into muscles and fatty tissues, we should eat our carbohydrates later in the day so we can burn fat as fuel during the day.
The problem with both of these ideas is that there is no solid research to back them. Instead, focus on overall daily caloric intake and the quality of those calories when trying to lose weight and eat your carbs whenever YOU feel best eating them. If eating carbs in the morning causes you to crash and feel tired and groggy later in the day, you can try eating the majority of carbs at night.
Eat Multiple Small Meals Per Day
You've more than likely heard the weight loss advice to eat multiple (5-6) small meals a day and to always have breakfast in order to jump-start your metabolism and keep it going throughout the day. Again, research has not shown this to have any significant effect on weight loss or metabolism. While it is true that digesting food does slightly raise metabolism, an occurrence called the thermic effect of food, it is the total amount of food and the quality of the food that determines the the energy required to digest a meal. This means that regardless of how many times per day you are eating, as long as you are taking in the same amount and quality of calories, the thermic effect will be the same.
The other argument in the case of multiple small meals per day is the argument that multiple small meals help to balance blood sugar levels and prevents large blood sugar spikes caused by fewer larger meals. While those consuming less frequent, larger meals may have higher blood glucose responses, research shows that their daily average blood glucose levels are actually lower than those consuming multiple meals per day. A little bit of exercise pre- and post-meal can also help reduce blood glucose spikes. Taking in fewer and larger meals with a short 15-20 minute walk post-meal or a few air-squats (or your favorite body weight exercise) pre-meal may actually be better for managing blood sugar levels than multiple small meals per day.
What IS Important When It Comes To Eating
The quality of what you are eating. Eat high quality, minimally processed foods.
Overall daily nutrient/calorie intake. WHEN you are eating doesn't matter as much as HOW MUCH and the QUALITY of what you are eating.
How you are eating. Eat slowly and mindfully and stop when you are satiated.
Why you are eating. Are you eating because you are hungry or are you eating because you are bored or stressed?
Consistency. The best diet is one you can stick to.
Finally, if you've covered all of this and you're ready to take on nutrient timing then what is important is really whatever works best for you!