Importance of CHO & Timing: Quick vs. Slow CHO When and What to eat.

Now I am a sports dietitian so I really focus on prime fueling for active individuals. Carbohydrates are foods we typically think of as bread/grains, sugar, fruit/vegetables. CHO are also in things such as processed and ultra processed foods (cakes, cookies, “healthy” snacks, soft drinks and more).

CHO account for 4 calories per gram and is digested, absorbed, and further processed into ATP and used as a source of energy. Something very important I want to stress is that ALL Fruit, vegetables, grains, starches, EVEN protein can be broken down to our simplest forms utilized during metabolism (GLUCOSE). What I want to uncover is when certain ”forms” of CHO are more appropriate at different times of the day, around our training, or maybe even considering your diet as a whole. Glycemic Index and Glycemic Load are often spoken about with CHO education. To simply define these terms:

Glycemic Index provides a way to rank CHO-rich foods according to the blood glucose response after these foods are ingested. It is calculated by measuring the incremental area under the blood glucose curve after ingestion of a test food providing 50g CHO compared to a reference food (glucose or bread).

• Stick to Low GI pre- exercise

Utilize moderate to high GI foods peri-exercise

Glycemic Load: considers both GI and the amount of CHO consumed. This is mostly preferred over GI these days. GL= GI x dietary CHO content. GL is almost always less than the GI of a food.

What are they?

Fast or SIMPLE carbohydrates are essentially as it sounds It is a quick energy source (meaning we can create ATP quickly through digestion and metabolism), and it can be utilized immediately to provide ENERGY for our workouts. These sources often cause a more rapid spike in our blood sugar levels due to the “ease” of absorption resulting in an insulin response. They provide SHORT TERM energy, meaning they wont fuel us for long. Foods we could associate as Fast CHO are things such as: refined grains, sugary drinks( gatorade, fruit juice), glucose in its simplest form table sugar, honey, maple syrup that can be broken down quickly and used immediately. From a sports performance side I may use Simple CHO when speaking about sugars that the body can absorb quickly (certain fruits, sugars etc.)

The best example I can give is that a marathon runner may carry glucose tabs which are purely straight sugar sometimes blended with other disaccharides fructose, sucrose that they can consume while running to consistently supply their body with ATP during such an extensive event.

Slow or COMPLEX Carbohydrates are sources that require a longer time through the entire process of digestion, absorption and metabolism due to higher amounts of fiber (which slows gastric emptying) and therefore takes longer for all the nutrients to be separated, and pass the intestinal barrier. These sources are often more satiating due to smaller amounts of fats and proteins within the main CHO itself. These CHO in turn show slower rises in blood sugars and we typically do not see drastic spikes compared to simple CHO sources. These may include fruits and vegetables, whole grains/starches, beans and lentils. Often these have a Lower GI foods that give a sustained release of glucose into the blood. These carbs are great for post workout meals as well as regularly scheduled meals.

When do I need to consume each ??

For Simplicity:

Simple CHO:

Before or during workouts depending on intensity and duration. For higher intensity aerobic training (cycling, metabolic training). I preach 15-30g 5-30 minutes prior of Simple( easily digestible) CHO sources prior to exercise, especially if you're not a big breakfast person. This will help to avoid tapping into energy reserves such as our precious lean muscle to provide energy during our workout. For example, maybe ⅓ of a gatorade, 2 cuties, 1 piece of a nature valley crunch bar, ½ r 1 whole gogo squeeze. Yes this will slightly count towards your macros nut you can adjust throughout the day. However, you may notice a difference in your energy levels while you workout and even recover with a little tiny bit of fuel in that gas tank!

Complex CHO:

At meals and snacks! All our meals should incorporate complex CHO packed with fiber and nutrients to provide satiating meals and proper control of our blood glucose spikes and insulin response. This becomes a key focus as we age to have tighter regulation of our blood glucose for adequate health and rapid spikes and lows are something we want to avoid, as well as chronic highs.

Prior

5-30 min prior to exercise (mostly aerobic): Choose easily digestible (mostly simple) forms of CHO ranging from 10-30g based on needs and exercise intensity.

60 min prior to exercise

2-4 hours prior to exercise: CHO rich “complex CHO” helps restore liver glycogen, especially after an overnight fast, increases muscle glycogen stores if not resorted from previous exercise sessions, and prevents hunger that can impair performance.

Post

Just like protein CHO consumption post- exercise is necessary to restore liver glycogen and is needed for proper recovery.

Consume CHO ASAP after exercise along with protein(~20g) to maximize recovery. Professionally I would say 30 min- 90 min post exercise.

Low GI, nutrient dense CHO sources (brown rice, sweet potatoes, oatmeal, vegetables, fruit, whole grain bread).

Closing Notes:

Why eat fast and Slow CHO paired with training ? Simple answer:

As a performance dietitian I would likely have a hard time believing you can gain muscle mass and lose weight cutting out single macronutrients such as fad or under researched diets that are promoted in today's diet culture. However, if we have time during this challenge I'll dive into some pros and cons and the research behind certain forms of “eating patterns/diets” (keto, intermittent fasting etc).

Studies are mixed on evidence of using specific GI prior and during exercise. Instead the Type, timing, and amount are more of our concern.

Let me clarify based on research that high GI foods (glucose), immediately before anaerobic exercise (weight lifting, sprints) will not necessarily result in a quick burst of energy. Remember back to our metabolic pathways. Our liver stores enough glycogen as well as creatine phosphate and muscle glycogen to provide energy for those anaerobic tasks.