What and When You Should Eat

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It’s not just what you eat but when you eat that matters. The perfect food for one situation may be horrible for another. Nutrient timing is a science that athletes use to try to get the most out of every calorie they consume. Not everyone needs an athlete’s level of efficiency, but all of us will benefit from a basic understanding of nutrient timing.

This is 911, need-to-know info only. To keep you focused on the big picture, I’ll begin with an example at the extreme end of nutrient timing. If the average Joe followed the same diet as an Ironman triathlete, he’d likely have type 2 diabetes in a matter of months. Conversely, if someone tried to complete an Ironman on even the healthiest version of a low-carb diet, that person would either be forced to quit or die. This is not just because either diet would mean eating too much food or too little food. Different foods cause the body’s metabolic process to react in different ways; and various activities should be fueled using various means.

Let’s begin by looking at our possible fuel sources:
Carbohydrates
Are fuel only. They aren’t stored in body tissue, only in the blood and liver as glycogen, which needs to be burnt off. They are essential for high-level functioning like running fast, lifting heavy things, and thinking. They are digested and put to use by your body very quickly. If you eat more than you burn, your body will convert them to be stored in adipose (fat) tissue.

Proteins
Called the body’s building blocks. Hence, you need them to rebuild tissue that breaks down daily. You digest proteins slowly, and at a certain point, your body just can’t assimilate them. Therefore, it’s important that throughout the day you eat foods that are high in protein.

Fats
Help regulate all of your bodily functions. They are dense and contain over twice the calories of proteins and carbohydrates. While they are vital for our health, it’s easy to eat too much of them, which will result in unwanted fat tissue on your body. You digest fats slowly, and fats will also help slow the digestion of anything else you eat. Fats are also your backup fuel source, though they can’t be put to use right away the way carbs can.

Fiber
Categorized as a carbohydrate, it is not a source of fuel as it has no calories. It’s the indigestible part of a plant and is of vital importance in your diet because it regulates the absorption of the foods you eat. It also helps us feel full. Most of us don’t eat enough fiber, and that’s a big part of the obesity problem.

Alcohol
Not really a food source but something we tend to consume. It has nearly twice the calories of proteins and carbs (though it lacks fuel) and digests rapidly. Its only healthy function is that it seems to make us happy. Studies indicate this is a good thing, as those who consume alcohol generally live longer than those who don’t, but from a purely nutritional standpoint, it’s not so hot because you’re getting calories without any upside. Its use should be strategic and regulated for best results.

Now let’s look at the various situations we face daily, at least on most days—hopefully.

Relaxing
This is when we’re sedentary both physically and mentally. In a relaxed state, you burn very few calories because your body is engaged as little as possible, hence the relaxing.

Sedentary work
When we’re at work or school. Our bodies aren’t moving, but our brains are engaged. The brain runs on glycogen, which is blood sugar fueled by carbohydrates.

Low-level exercise
Like mowing the lawn, cleaning the house, or going for a walk. This breaks down body tissue, so you’re burning calories, but it’s not intense work. Therefore, it can be fueled by your stored body fat. Your body tries to fuel its low-level outputs by mobilizing fat stores because this saves its limited glycogen for emergency situations.

High-level exercise
Fueled by glycogen. When you really have to get after it, all sorts of hormones go to work, and your body burns its blood sugar. Body-tissue breakdown is rapid, and your stored blood sugar (glycogen) won’t last much more than an hour.

Sleep
A very active time. Deep sleep is where your body works the hardest to repair itself. You need nutrients to make these repairs, but it’s better if you aren’t mucking up the process with digestion. This is why you hear that you shouldn’t eat too much at night. It’s best to eat early to allow most of the digestion to happen while you’re awake, thus allowing your body to use all its energy for recovery during sleep. It is worth noting here that it’s better to eat before bed if you need the nutrients—don’t skip them. Your body can’t repair itself without nutrients, and recovery from breakdown is why we eat in the first place. Next, let’s take a look at an important word you need to know: insulin.

Insulin
Wikipedia tells us that insulin “is a hormone that has extensive effects on metabolism and other body functions, such as vascular compliance. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle, and stopping use of fat as an energy source.” Okay, that’s a little scientific, but look at all the things we’ve already referenced: hormone, glycogen, metabolism, and fat as an energy source. Even if you don’t fully comprehend “vascular compliance,” you can tell that insulin is something important in today’s discussion.

Sure enough, it’s the only hundred-dollar word we need to know today. Your body’s insulin response is the main reason you want to eat certain foods at certain times, to do certain things.

Putting it all together
Now let’s take what we’ve just learned and put it to use. For most of us, nutrient timing is pretty simple. The next thing to consider is what you’re going to be doing or what you just did. As I said before, what you eat should be based on this. You’ve probably heard about the evils of sugar, or maybe even the glycemic index. Using the science of nutrient timing, you can turn sugar into something healthy because it’s the only thing that transports nutrients into your blood quickly enough to be of service during and after hard exercise.

Essentially, sugar or other easily digested carbs (the less fiber the better) promote an insulin release. This speeds the transformation of carbohydrates into glucose in your blood. As your glycogen stores are depleted during exercise, recharging them with sugar minimizes the damage done by the breakdown of tissue during exercise. Therefore, sugar, the oft-vilified ingredient, is actually your body’s preferred nutrient during times of excessive stress and tissue breakdown.

Pretty cool, huh? The bad news is that this miracle nutrient is not good for you when you’re not doing intense exercise, which for almost all of us is most of the time. In fact, sugar’s very bad for you because the insulin response that was so fabulous for you when you were bonking (glycogen depleted) is not so fabulous for you when you’re sitting in front of the boob tube.

Remember this from the Wikipedia definition of insulin, “stopping use of fat as an energy source”? That’s bad when you’re sitting around. Remember how one of dietary fat’s responsibilities is to fuel you during low-intensity exercise? Well, when sugar causes your insulin to spike, it cuts off that process. Now not only are you not burning body fat for low-level outputs, you’re trying to force your body to use its glycogen. Double bad.

Unless you’re exercising, sugar intake should be minimized. During these times—which is most of the time—your diet should consist of a mixture of proteins, fats, and complex carbohydrates. The latter are natural sources of carbohydrates that generally come with fiber, which regulates the insulin response. Whole fruit, a simple carbohydrate by definition because it contains fructose (a sugar), always contains fiber and, thus, can be treated as a complex carb. Fruit juice, and other such stuff, is processed; it, along with processed complex carbohydrates like white rice, can cause an insulin response, so these types of foods should be used more like sports foods than staples.

It’s also important to note that combining all these different nutrients slows sugar’s ability to incite insulin into action. Therefore, a little sugar like a dessert after a well-rounded meal is buffered by the meal. The calories and lack of decent nutrients (processed sugar is devoid of most nutrients, except for energy) still count toward your overall diet, but at least you don’t have to worry about an insulin spike.

So the main point of this article is very simple. You should eat small, well-rounded meals most of the time. These should include some proteins, some fats, some fiber, and some carbs. During (only if it’s a long workout) and after hard workouts, you should supplement your diet with sugar or simple carbohydrates. After this, you should go back to eating well-rounded meals again.

Sports nutrition has evolved this process even further. In nature, foods are generally slow to digest. Nature’s great sports foods are things such as bananas and figs. These are sugary but still contain fiber and other nutrients. Science has found ways to make foods that are even more efficient during sports. These basically manipulate pH levels and process the sugars to speed them into your system. Outstanding when you need it. Terrible when you don’t.

They’ve even taken this a step further by finding a ratio of other nonsugary nutrients (like protein) that can be transported by the sugar to give you a further benefit. Beachbody’s Results and Recovery Formula uses this science. When you’re bonking during a hard workout, it speeds nutrients that are essential for quick recovery into your system as quickly as possible.

I can’t stress how important it is that sports fuels be used for sports performance only. Gatorade, soda, and all sugar candies (hey, no fat!) all function as the poor man’s sports foods. Unfortunately, those perusing the Quick Stop generally aren’t trying to fuel up after doing Plyo X, and therein may lay our obesity trend.

In case the topic is still a bit fuzzy, let’s use the above logic on the examples in the intro: An Ironman athlete is doing intense exercise for 10 to 12 hours or more. During this time, that athlete is mainly burning glycogen, which is gone after an hour or so. The athlete burns stored fat, too, but this is limited in its effectiveness. To race, the athlete must replenish with sports foods because they contain the only nutrients that the athlete will digest fast enough to help. To complete an Ironman, especially at your physical limit, it may take 5,000 calories coming mainly from sugar.

This is a sports-specific diet only. Someone trying to eat that way during a viewing of the Lord of the Rings trilogy would be lucky to stay out of the emergency room. Conversely, if you tried to maintain a 25-mph speed for 8 hours on your bike while munching on raw spinach and lean steak, you’d bonk so hard you’d be praying to get yanked from the race at the first checkpoint. That should cover your 911 on nutrient timing. Next time, we’ll move on to the topic of supplements. Are they magic pills, overhyped placebos, or something in between?

Hydration for Athletes

Water
Possibly the most under-emphasized aspect of sports nutrition, hydration can make or break an athlete’s performance. While fuel depletion during exercise can impair performance, inadequate water not only impairs exercise capacity, but can create life threatening disturbances in fluid balances and core temperature. With as little as 1% of body weight lost in fluid, athletes can experience thirst, fatigue, and weakness. (1) Thirst drives a person to drink, but it can actually lag behind the body’s need. When too much water is lost from the body and not replaced, dehydration develops. Dehydration refers to an imbalance in fluid dynamics when fluid intake does not replenish water lost. On the flip side, water intoxication occurs with excessive water intake or kidney disorders that can reduce urine output. In healthy individuals, dehydration is more common than water intoxication, but appropriate water balance is crucial to optimal performance and ultimately survival.

  • Water and Body Fluids

Water constitutes about 60 percent of an adults weight and it is the medium in which all life processes occur, including:* Carrying nutrients and waste products through the body* Maintaining the structure of large molecules* Acting as a solvent for minerals (i.e., sodium and potassium) and other small molecules* Acting as a lubricant and cushion* Maintaining blood volume* Helping the body regulate temperature.  Every cell in the body contains fluid specific for that cell called intracellular fluid, and around it is extracellular fluid. These fluids continually lose and replace their components, but the composition of each compartment remains remarkably constant. Because an imbalance can be devastating, the body continually adjusts water intake and excretion as needed. This type of balance is referred to as homeostasis. The body must excrete a minimum of about 500ml (about 2 cups) of water each day as urine to eliminate waste products that the body makes through metabolism. Above this amount, the body adjusts by excreting excesses to balance intake. In addition to water lost in the urine, the body also loses water from the lungs as vapor and the skin as sweat. The amount of fluid lost depends on the environment (heat and humidity), and physical conditions such as activity. On average, the body loses about 2.5 liter/day. Fluid maintains blood volume, which influences blood pressure. The homeostatic balance of fluids and solutes in the body is carefully regulated by the kidneys with assistance from several hormones including antidiuretic hormone (ADH) and aldosterone. The primary solutes that are involved in maintaining fluid balance are sodium, potassium, proteins, and glucose. Adequate intakes of water and electrolytes maintain hydration levels and regulate fluid shifts between the intra- and extra-cellular compartments. To maintain water balance, intake from liquids, foods, and metabolism must equal losses from the kidneys, skin, lungs, and GI tract.

  • The Needs of the Athlete

One of the primary functions of water for all individuals, especially athletes, is thermoregulation. A person can tolerate a drop in body temperature of 10 degrees (c), but an increase of only 5 degrees (c). Heat generated by active muscles can raise core temperature to levels that would incapacitate a person if caused by heat stress alone. (2)The body uses three mechanisms to dissipate heat:* circulation* evaporation* hormonal adjustment. The circulatory system works to deliver warm blood to the body’s shell. This produces the typical flushed face. Sweating begins within several seconds of the start of vigorous exercise and this evaporative cooling controls heat dissipation during exercise. Lastly, because sweat contains water and electrolytes, the body makes hormonal adjustments to help prevent the loss of salts and fluid. When the fluid lost in thermoregulation results in dehydration and a drop in blood volume, the end result produces circulatory failure and core temperature levels can increase to lethal levels.

  • Water Replacement

Total water intake at the reference level of 3.7 liters for adult men and 2.7 liters for adult women per day covers the expected needs of healthy, sedentary people in temperate climates. The obvious dietary sources of water are water itself and other beverages, but most foods contain some water as well. Most fruits and vegetables are almost 90% water, and many other foods like meats and cheese are approximately 50% water. The body also makes water during metabolism, when energy-yielding nutrients break down and their carbons, hydrogens, and oxygens combine to make carbon dioxide (CO2) and water (H2O).According to the Dietary Reference Intakes: The Essential Guide to Nutrient Requirements, published by the Institute of Medicine (3), most people get adequate fluids by drinking when they’re thirsty. However, the report does add that prolonged physical activity and heat exposure will increase water losses and therefore may raise daily fluid needs. Very active individuals, who are continually exposed to hot weather, often have daily total water needs of six liters or more. Both heat acclimatization as well as nutrition intervention is indicated for this population. According to the American College of Sports Medicine, general guidelines for fluid replacement are as follows: (5) Consume a nutritionally-balanced diet and drink adequate fluids during the 24-hr period before an event. Drink about 500 ml (about 17 ounces) of fluid about 2 hours before exercise to promote adequate hydration and allow time for excretion of excess ingested water.* During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace all the water lost through sweating or consume the maximal amount that can be tolerated.* It is recommended that ingested fluids be cooler than ambient temperature [between 15 degrees and 22 degrees C (59 degrees and 72 degrees F])] to enhance palatability and promote fluid replacement.* Addition of proper amounts of carbohydrates and/or electrolytes to a fluid replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance. Water loss by sweating peaks at about 3L per hour during intense exercise in heat. However, just about any degree of dehydration can impair performance. Adequate fluid replacement sustains the body’s potential for evaporative cooling. Rehydration protocols are often based on water lost as measured either by urine color, urine specific gravity, or changes in body weight.(4) If collecting urine is not feasible, sweat loss as reflected by weight loss can be used. An athlete’s pre and post workout (or event) weights are taken and whole body sweat rate can be calculated by dividing the sweat loss by the time period of collection. The following equation can be used to determine volume of fluid lost: (5) Sweat loss = (body weight before – body weight after) + amount of fluid intake – toilet loss. Alternatively, taking a simple measure of body weight each morning after emptying the bladder can show a pattern of hydration over time, provided gains or losses of fat and muscle tissue are not also taking place. Fluid balance, electrolyte homeostasis, cardiovascular function, and thermoregulatory control are intimately linked to fluid consumption and each has a major impact on health and performance. Fluid replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. Athletes and their coaches should be aware of fluid replacement needs, and develop strategies and protocols to insure athletes drink enough to keep pace with sweat loss.