Ketogenic, Paleo, Fasting: Which High-Performance Diet is Right for You?

Ketogenic, Paleo, Fasting: Which High-Performance Diet is Right for You?
Presented by Spartan Training®

Let's talk about the ketogenic diet, keto macros, the paleo diet and fasting. Which is best for you? Remember when you were a kid and one of your friends had a seemingly cool idea that your parents knew wouldn’t end well for you? The conversation went something like this:

You: “But Mom, Tommy gets to go.”

Mom: “If Tommy was going to jump off a bridge, would you jump too?”

You probably walked away pissed, but snuck out to go anyway. So why do we pull the same move as adults—especially when it comes to nutrition? This is the case for many people attempting a new diet. It’s human nature. We see something that looks good—a diet getting results, our favorite celebrity or athlete touting their eating habits, the latest documentary—and we instantly jump on board proclaiming that we’ll start eating that way tomorrow! What?!

Hold on. Slow down. Take a breath. And think. The wrong approach, especially for an athlete, can mean setbacks in your training due to inadequate caloric intake, electrolyte imbalance, or suddenly reducing a primary source of energy (such as carbohydrates). With so many nutrition approaches out there (Paleo, ketogenic, intermittent fasting, and more) it pays to do your research before deciding which is best for you. Let’s dive into a few diets that can have major health benefits when done right.

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Ketogenic & Keto Macros

The basics: Keto macros are what make this diet controversial: High fat, moderate protein, and low carbohydrate intakes. The keto macros protocol reduces carbohydrate intake to a point where glucose supply for energy creation is limited. This encourages the body to convert fat into fatty acids and eventually ketones to meet fueling needs. The state of ketosis is truly identified through blood testing for ketone levels, but those doing it right (and usually after about six months) can use more of an intuitive feel for their ketosis state.

Target blood ketone levels vary by your desired outcome:

Weight loss: above 0.5 mmol/L

Improved athletic performance: above 0.5 mmol/L

Improved mental performance: 1.5–3 mmol/L

Therapeutic (e.g., to prevent or manage certain illnesses): 3–6 mmol/L

What to know: When done right, and for the right person, applying keto macros has been shown to decrease inflammation, drastically improve body composition, help reduce symptoms of autoimmune disease, and reduce seizure activity for those with epilepsy. When done wrong, a ketogenic diet can cause insufficiencies of essential macro and micronutrients, result in reduced muscle mass, strength loss, and brittle hair and nails.

Fails to avoid: Make sure to know which fats are considered healthy fats (see A Quick Refresher: Types of Fats) that will not only fuel a ketogenic diet but also support the longevity of your heart and body. Make sure your proteins are from high-quality sources as well as plant-based sources. With your carbohydrate intake low, make sure you eat quality complex carbohydrates that will optimize vitamin and mineral intake, fuel a healthy gut, and meet your training needs. Don’t box yourself in to a specific ketogenic approach either. Carb cycling can be beneficial for high-intensity training regimens and for those new to the diet.

Related: How to Get Started On the Ketogenic Diet


The basics: This approach to eating incorporates foods that would have been found during the Paleolithic Era (roughly 2.5 million years to 10,000 years ago). Foods avoided are grains (e.g., wheat, oats, and barley), legumes (beans, lentils, peanuts, and peas), dairy, refined sugar, added salt, potatoes, and highly processed foods in general. Simply based on what foods it encourages, the Paleo diet tends to be higher in protein, low in carbohydrates, and moderate in fat, but this varies based on the person and their goals.

What to know: The Paleo diet has been helpful for many as a weight-loss approach, but has also been beneficial for those with autoimmune disease and digestive issues.

Fails to avoid: The challenge here being to stick with it long term without feeling limited. If you view the Paleo approach as a lifestyle and continue to learn about the philosophy, you’ll be able to fill your day with lots of nutritious foods without a problem. But simply Googling a Paleo meal plan and looking at the “avoid” list can make you feel boxed in.

Related: The Right Way to Eat a Paleo Diet: 6 Tips to Live By

Intermittent fasting

The basics: This is not a diet, but rather an eating pattern. Intermittent fasting is gaining ground as a great approach for weight loss, adapting to fat metabolism, and simply to make meal planning easier. There are a variety of common fasting protocols to choose from such as

  • 16 and 8: fasting for a 16-hour window and eating within an 8-hour window;
  • 24-hour fast: fasting for a full 24 hours (sometimes stretched to a 36- or 48-hour window); or
  • 5 and 2: a 5-day eating window with 2 days somewhere throughout the week where you consume 500–600 calories only, at one meal.

    Who it’s best for: Anyone can really get on board with intermittent fasting. Not only has intermittent fasting been a way to enhanced our body’s ability to convert fat to fuel, it has also made planning and prepping meals a heck of a lot easier by reducing the frequency of fueling.

    Fails to avoid: Before trying a fasting protocol, you really have to already be practicing good overall nutrition. If you hope to eat all the high-fat, nutrient-poor, fried, processed foods there are and then jump on a fasting protocol to melt it all away . . . not gonna happen. Athletes should also have a strategic plan around their fasting windows. For those who are new to fasting and aren’t fully fat-adapted, fueling around higher-intensity training may need some adjustment until your body can catch up.

    Related: Intermittent Versus Time-Restricted: Which Fasting Is Best?

    The approaches are simple enough, but succeeding in the long term while improving your athletic performance is going to take knowledge. Spartan has you covered. Check out our nutrition content to start learning the best nutrition practices for athletes now.

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