Where the Paleo Diet Falls Short

According to Dr. Robert Portman and Dr. John Ivy, the Paleo Diet falls short in relation to metabolic windows of opportunity in the body's 24-hour cycle.

Paleo Diet
Has the Paleo diet missed its target? According to Dr. Robert Portman and Dr. John Ivy, sports nutrition experts and authors of the book, Hardwired for Fitness, the Paleo diet fails to take into account the circadian rhythms of the body.

Although a number of iterations of the Paleo diet exist, the common definition goes something like this: Confine your food intake to meat, fowl, fish, vegetables, nuts, seeds and fruit; and avoid dairy, grains, legumes, sugars and processed foods.

The Paleo diet is often viewed as exceptionally low in carbohydrates, coaxing practitioners to reach for more protein and fat. Although following a diet free of processed foods is a good thing, Portman and Ivy say the Paleo Diet comes up short in relation to the metabolic windows of opportunity offered in the human body's 24-hour cycle.

It's about metabolic efficiency, not calories. This is the primary thrust of Portman and Ivy's nutritional model for health and fitness. One of the many sacred cows they work to slay is the old cliché about the bottom line of sports nutrition: "just make sure you eat enough calories to replace the ones you've burned."

The "calories ingested versus calories burned model"—in the spirit of the First Law of Thermodynamics—is part and parcel of most diet and nutrition books. Countless books, websites and apps are designed to make counting calories as easy as possible. But not only is this hard to do and hard to stick with, Portman and Ivy say it's not optimal to achieve the objectives athletes commonly wants to achieve with nutrition, such as:

  1. Providing enough energy for training and performance.
  2. Dialing in body composition and weight.
  3. Providing the nutrients necessary to rebuild muscle tissue after workouts, ultimately improving performance.

Portman and Ivy recommend a plan more in concert with the Second Law of Thermodynamics, as in the efficiency of a system. In other words, rather than focusing on diet plan that fills up the tank enough to drive a certain distance, think of nutrition as a way to make your engine run as efficiently as possible.

To do this, Portman and Ivy assert, you need to tune your eating to the inherent rhythms of our 24-hour genetic clock. By calibrating your meals to specific macronutrient ratios, you can ride the right metabolic waves to maximize protein synthesis at the right time and unleash high levels of energy at the right time.

Breakfast: 60% carbs, 20% protein, 20% fat. 

Stress hormone levels in the form of cortisol spike in the final hours before you wake up after a night of fasting, and studies show that breakfast is the most satisfying meal of the day. While you're sleeping, your body uses cortisol to break down muscle protein to provide energy. This is why skipping breakfast is a killer for athletes—your cortisol levels stay high, and muscle protein continues to break down into the mid-morning. A high-carbohydrate breakfast lowers cortisol levels and provides a base of energy for the day.

Lunch: 62% carbs, 7% protein, 31% fat.

The body's energy circuits function at their best during this time of day, and your muscles burn carbohydrate at peak efficiency.

Post-Workout Snack: 25% carbs, 50% protein, 25% fat.

According to Portman and Ivy, the late afternoon is the best time of the day to exercise. A 100-calorie snack, in which half of the calories come from protein and the rest come from equal measures of carbohydrate and fat, ingested within 30 minutes of finishing a workout will promote muscular recovery, they say.

Dinner: 25% carbs, 35% protein, 40% fat. 

When it comes to your metabolism, the early evening offers an optimal rebuilding window. According to Portman and Ivy, rebuilding circuits switch on as activity circuits power down. This ties in to why a late afternoon workout has ancillary benefits: by following the late afternoon workout with a high-protein dinner, an athlete can triple his or her rate of protein synthesis.

Bedtime Snack: 20% carbs, 80% protein, 0% fat. 

Portman and Ivy counsel against waking up and eating in the middle of the night, but a 100-calorie protein drink or small serving of turkey right before bed time can help diminish the amount of protein breakdown that happens during sleep.

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