Think back to the last thing you ate. Was it a bagel for breakfast? A steak for dinner? How did you feel afterward? According to The Metabolic Typing Diet book, what you eat may alter your body’s response. Forms of metabolic typing have been developed and studied for years, with one idea building upon another. Most recently, this diet trend has sparked the interest of many individuals looking for the latest diet recommendations.
What is Metabolic Typing Diet
This idea of metabolic typing diet first started in 1956 when a doctor by the name of Roger Williams wrote a book asserting that humans are inherently different, and therefore their metabolism and dietary needs will be different… Makes sense!
Although the book did not gain popularity, it did grab the attention of a man from a small town in Texas. The man William Donald Kelley took this idea and grew to develop Metabolic Type Dieting based on his own experiences and research.
The basis of this diet, according to Kelley, is attributed to the body’s autonomic nervous system, which is broken down into the sympathetic and parasympathetic systems. These two branches oppose one another in a variety of body responses, including heart rate and digestion.
He claims that individuals are strongly influenced by one of these branches of the autonomic nervous system over the other and that specific nutrients can trigger those systems. Kelley emphasizes that eating specific foods based on your body’s response can aid in overall health benefits and disease prevention. The question is, is there any truth behind this? Let’s explore.
3 Different Metabolic Types
This diet is broken down into three different categories, fat-protein efficient, carbohydrate efficient, and mixed efficient based upon results from a questionnaire. Let’s take a closer look at each type:
Fat-Protein efficient (fast oxidizers)
Based on this diet type, the body is strongest in the parasympathetic branch of the autonomic nervous system. This results in faster oxidation (aka: breakdown) of carbohydrates. Hence, a high-carbohydrate diet can have adverse effects on the energy production of fast oxidizers. This can result in frequent hunger, tiredness and fatigue.
On the other hand, a diet consisting of increased protein and fat can help balance their energy production. A fat-protein efficient diet should be focused on higher protein foods, such as red meat and seafood.
A high protein, high fat, low carbohydrate diet is not new to the nutrition world. Many diets have been based on this exact same premise, such as the Ketogenic diet or Atkins diet.
In fact, numerous celebrities have endorsed this type of diet plan. Risks associated with this type of diet plan can include elevated cholesterol levels, increased inflammation within the body, and other cardiovascular risk factors associated with high saturated fat intake.
However, if there is a stronger focus on unsaturated fats this can be very beneficial. Foods high in unsaturated fats include avocado, nuts, and olive oil.
Carbohydrate-efficient (slow oxidizers)
Opposed to a person who is fat-protein efficient, this diet type is stronger on the opposite branch of the autonomic nervous system, the sympathetic branch. This requires you to consume more carbohydrate-based foods in order to strengthen the parasympathetic branch.
With this diet type, you are encouraged to follow a low-fat, low-protein diet that is high in fruits, vegetables, and whole grains.
Mixed efficient (mixed oxidizers)
As the name suggests, this diet typing indicates a person has a balance of both the parasympathetic and sympathetic branches of the autonomic nervous system. Therefore, your diet should be a mix of protein, fat, and carbohydrates.
Diet Choices Based on Metabolic Types
Now onto the question, everyone wants to know, “what CAN I eat?” Below are some food suggestions based on your metabolic type:
Fat-Protein Efficient: Red meat (pork, steak, lamb), Dark meat (chicken, turkey), Seafood (tuna, salmon), Whole fat dairy, Limited carbohydrates
Carbohydrate Efficient: Vegetables, Fruits, Lean meat (chicken breast), Low-fat dairy, Limited fat, and protein
Mixed Efficient: Mixed of both diets, Minimal restrictions
Benefits of Metabolic Typing Diet
Metabolic typing has a strong focus on a more holistic approach versus the traditional medical approach to overall health. The authors of The Metabolic Typing Diet make several large claims regarding the health benefits of this diet including reversing chronic disease. They go on to state curing hypertension can be as simple as adjusting the macronutrient distribution in your diet versus traditional medication.
Although they provide several analogies on how the body systems influence one another and work together, they provide no evidence to these claims, which is a red flag. Additional benefit claims include weight loss, cessation of digestive issues, removal of anxiety and depression, improved athletic performance, mental clarity, and sustained energy throughout the day.
Bottom Line – A Dietitian’s Perspective
The research on the effectiveness of this diet is very sparse. One small study of 33 individuals out of Taiwan found that individuals who were fat-protein efficient had more significant improvements in weight loss than the carbohydrate-efficient group. However, overall, both groups and genders had weight loss during the 4 weeks of the study.
This diet could possibly be a future recommendation for individuals looking to lose weight. However, an immense amount of additional evidence is needed to draw these conclusions. In addition, basing diet solely on a questionnaire could lead to potential health consequences if the individual has other existing conditions. For example, if an individual with a history of heart disease is told they are fat-protein efficient, a diet of red meat and full-fat dairy could be cause for concern…yikes!
When looking at the positive aspects of this diet, it focuses on prevention versus a treatment approach (bonus points!). In addition, there is a focus on healthier foods for the carbohydrate-efficient individual by promoting whole grains, fruits, and vegetables.
On the other hand, the fat-protein efficient diet seems to be very similar to the Atkins diet, which is very restrictive and can lead to elevated cholesterol levels. Overall, diet customization can be the key to successful control and/or the treatment of nutrition-related diseases and conditions. As the dietitian’s motto goes, “one size does NOT fit all.” Thus, opting for a customized meal plan tailored to your bodily needs is highly recommended. However, this diet sounds too good to be true as the claims are very extravagant without any evidence these changes are effective and safe. Proceed with caution!
You can learn more about Metabolic Typing Diet by reading the book
About the Author
Maggy Doherty is a Registered Dietitian and owner of her own nutrition private practice, Doherty Nutrition.
As a UCLA student-athlete on the Women’s Diving team, she learned how to use food to take her health and performance to the next level.
She earned her Master of Science in Nutrition at the University of Illinois and has practiced as a clinical dietitian at Dallas’ Parkland Hospital.