A targeted ketogenic diet (TKD) is a variation of the keto diet. Other variations include a cyclical ketogenic diet or a modified, slightly higher carbohydrate ketogenic diet, neither of which will be discussed here. A TKD is not recommended for beginners on the keto diet. It is only recommended after 4 weeks of using the standard ketogenic diet and ensuring you are in ketosis.
Who uses a TKD?
A TKD is used for athletes who are working out at high intensities (HIIT) and/or heavy resistance training that need to maintain high performance levels. A recreational athlete may or may not want to try a TKD depending on their exercise goals.
For example, an athlete playing soccer will be at high intensities during sprints. This same athlete on a keto diet will notice they cannot achieve the same speed or intensity when on keto. If this athlete is competitive and wants to maintain their speed during sprints, they will try a targeted ketogenic diet. If this athlete is okay with decreased performance during sprints, they will maintain a standard ketogenic diet.
When to Use TKD?
A targeted ketogenic diet involves a regular ketogenic diet for the majority of the time. Only around exercise periods (HIIT, intense sports or heavy resistance training) does the targeted ketogenic diet come into play. An athlete using TKD will increase carbohydrates pre-exercise, post-exercise or both depending on the goals.
Why Use A TKD?
The fast-twitch fibers in your muscles require glucose to perform. Fast-twitch fibers are used in high intensity activities like sprinting or heavy weight training. These fibers CANNOT get energy from ketones.
If you are active in HIIT activities like cross-training or sports, you will notice a decrease in performance at the higher intensities. Above 70% intensity your body begins to require glucose for muscle energy, even if you are keto adapted. As the intensity gets higher, your body requires more glucose, less ketones.
How a Targeted Ketogenic Diet Works
Amount of Carbs
It has been noted in some studies that during high intensity, 2-3 grams of carbs are burned per minute! If you were doing a high intensity activity for 30 minutes, this would amount to 60-90 grams of carbs!
However, most athletes are not performing at that level for the entire 30 minutes of exercise. That would be sprinting for 30 minutes straight. If you are, kudos to you. But for carb loading estimations, I usually estimate that you are performing at extreme high intensity for about 1/4-1/2 the workout. If you have a heart rate monitor (the one we use), you can use during your next workout to get a better estimation of how long you perform at high intensity.
In any case, the average recommendations tend to fall around 20-30 grams of carbs ingested to start. It took a long time to get into ketosis, so you wouldn't want to eat too many carbs and go backwards. As your experiment with your amount of carbs, your range could end up being 15-45 grams of carbs for every 30 minutes of an intense workout.
When to Eat Carbs
Before a short bout of high intensity exercise, add the intial 20-30 grams carbs about 30 minutes pre-exercise to get them into your blood-stream and available to the muscles. Adding carbohydrates more in advance of 30 minutes may begin to mess with your ketosis; however, this is something you can play with if you think you'll be at high intensities for extended periods.
If you are working out for longer than 30 minutes, then add 20-30 grams every 30 minutes. So the timing for 1 hour intense workout should look something like this:
30 minutes pre-exercise: 20-30 grams carbs
0 minutes pre-exercise: 20-30 grams carbs
If you are nervous about your ketosis, we recommend starting with only the one 20-30 gram serving of carbs 30 minutes pre-exercise and see how you feel.
Not all sugar is created equal
When on a ketogenic diet, the carb you want to eat is dextrose, the form of glucose in food. Dextrose will be metabolized and go straight to the blood stream. If you eat fructose, it is first metabolized by the liver and can easily mess with ketone production (ketones are produced in the liver). Sucrose (table sugar) is a combination of dextrose and fructose, so is not recommended either. Candy like Smarties are one of the easiest to find sources of dextrose without fructose.
If you find there are times you'll be in an extended sports game, say 1.5 hours plus, the amount of Smarties necessary for the workout is just too much candy. It actually starts to make you sick to your stomach. Also during these extended games, it's necessary to add sugar throughout the workout. It may not be possible to chomp on Smarties during breaks. Instead opt for mixing dextrose (the cheapest dextrose we've found is here) into your water bottle so you can drink it throughout the game.
Post-exercise carbs are not as highly recommended as pre-exercise carbs when you're just starting out on a TKD. If you feel comfortable with a few more carbs not affecting ketosis, the only post-exercise carbs we recommend are a very small amount to help with muscle building after exercise and replenishing muscle glycogen. We recommend starting out at a small 10 grams of carbs post-workout and go from there.
If you ingested a lot of carbs pre-workout, then don't worry about post-exercise carbs at this time. Get comfortable with the amount you need for pre-workout before. Although it will be good to eventually get comfortable with giving your muscles the carbs necessary to reload the muscle glycogen.
A Few More Do's And Don't of A Workout
DO start out with 20-30 grams of dextrose 30 minutes before exercise. Note how you feel for next time and adjust the amount of carbs for the length of the workout.
DO give yourself a protein shake post-workout. The recommended intake is 20 grams protein after your workout. I recommend a whey protein shake because it is easy to obtain a pure protein supplement that does not contain sugar or fat.
DONT eat fat for an hour after working out. This is the one time we'll say not to eat high fat. Fat will suppress the insulin response and prevent muscle building and repair after a workout.
DO take your blood glucose and ketone levels before and after exercise. If you are just starting out, take measurements before you ingest dextrose and post exercise to determine if the amount of dextrose added was too much or too little. You can also determine if you had too few carbs if you got extremely fatigued during the workout.
DO start a spreadsheet and track your carb intake per workout, along with blood glucose and ketone levels. This will help you fast-track your way to optimizing carb intake and energy levels for intense workouts.
DON'T forget, as an athlete you'll want to pay special attention to vitamins and minerals like potassium so you don't get cramps during exercise. Keto dieters are especially vulnerable to potassium shortage.