Metabolic Types: Fast, Mixed, and Slow Oxidizers

What is metabolic typing?

flat lay photography of vegetable salad on plate

Metabolic typing is an individualized approach to meeting your nutritional needs that relies heavily on your rate of metabolism along with your genetics. Pioneers of metabolic typing believed the autonomic nervous system, which is basically your metabolic individuality, and your rate of oxidation, which is the rate your body converts food into energy, is what should be taken into consideration in choosing your diet.

Where your ancestors lived, the climate they lived in, and the foods that were available to them may also determine what you should eat. Most people are divided into different degrees of the three metabolism types. Either you are a protein/fast oxidizer, a carbohydrate/slow oxidizer, or a mixed, both fast and slow oxidizer. You can determine your oxidizer/metabolic type by taking a simple quiz that assesses your eating needs and desires here.

How does metabolic typing work?

Knowing the correct balance of fat, protein, and carbohydrates you should eat is the key to most eating issues.  Once you begin to feed your body right, it will naturally begin to heal itself. Your energy level will improve because you are feeding it the correct fuel. Eating for your type helps to optimize your blood PH since the same foods can be acidic for some types while alkalizing for other types. Eating the right diet also improves your oxidation rate, resulting in better utilization of the food you eat.

Those with chronic illnesses do not realize that the treatment may be as simple as eating the foods that are best for them and eliminating the foods that may cause trouble. The foods you eat may be the result of lifelong habits of the wrong choices. For most people, changing your eating habits can be difficult, but the difference can be like night and day.

Metabolic typing is divided into 3 types that require three different diets.

Fast Oxidizers (should focus on making sure their diet has enough protein and fat)

Slow Oxidizers (should focus diet on carbohydrates with a little less emphasis on harder to digest proteins and fats)

Mixed Oxidizers (should focus diet on a balanced intake of protein, fat, and carbohydrates, and sometimes those needs can change)

Your nervous system, divided into sympathetic and parasympathetic type, should also be taken into consideration, but I will write more about that in another article.

WHAT IS A FAST OXIDIZER?

A fast oxidizer or someone with a fast metabolism will rapidly convert food into energy. Fast oxidizers need to eat heavier proteins and fats that burn slowly to balance out their fast metabolisms and keep blood sugar levels stable.

While lots of people want to have a fast metabolism, keep in mind that a fast oxidizer will also burn through the micro-nutrients needed to make energy in the body as well.

B vitamins and magnesium can become depleted in a fast oxidizer if junk food is consumed. B vitamins and magnesium are micronutrients needed to convert food into usable energy.

The fast oxidizer still needs to consider the nutrient density of food to ensure adequate intake of B vitamins and magnesium for energy.

Tips for fast oxidizer, protein types:

  • Up to 40% of your diet can be from protein, 25 to 30 percent from fat and the rest carbohydrates, these amounts will always vary with the person
  • Eat flesh protein at least twice a day or with every meal. Fattier meats and fish work well for this type. Stay away from pork.
  • Eat fat with every meal but only the good fats like avocados, olive oil and coconut oil. Soybean and corn oils cause inflammation.
  • Remember fat does not cause weight gain, carbs cause weight gain
  • Eat your protein or meat first to help digestion
  • Stay away from sugar, it is especially bad for fast oxidizers
  • Eat only small amounts of fruit and eat them last, preferably with fats like olive oil or coconut oil
  • Eat a vegetable with every meal but no white rice, wheat, corn or potatoes (too high glycemic). Always add fat, but only after the vegetables are cooked.
  • Root vegetables can help if you want to gain weight but keep them to a minimum
  • Grains are not good for this type unless they are sprouted, because they block nutrients and are harder to digest.
  • Caffeine worsens any imbalance

WHAT IS A SLOW OXIDIZER?

A slow oxidizer converts food into energy at a slower rate. Healthy carbohydrates such as fruits, vegetables, and whole grains are best for a slow oxidizer.

You can think of the metabolic rate on a sliding scale from zero to one hundred. You can be anywhere on that scale with the middle indicating balanced and mixed oxidation or metabolic rate.

At each end of the sliding scale, you have either a fast oxidizer or a slow oxidizer. You can use the following symptoms to determine where you are on the metabolic scale to help guide you in eating the best foods for your metabolic type.

William Wolcott, the author of the metabolic typing diet, has in-depth questionnaires and diet plans for fast, slow, and mixed oxidizers.

SLOW OXIDIZER SYMPTOMS INCLUDE:

  • Lower body temperature or easily gets cold hand and feet
  • General fatigue or lack of energy
  • Craves sugar
  • Hypofunction of the adrenal and thyroid glands
  • Prone to constipation and sluggish transit time
  • Weight gain in hips and legs
  • Craves lighter, more hydrating foods such as fruits and vegetables
  • Feels weighed down and fatigued after eating heavier foods such as animal protein, fats, nuts, and seeds
  • Tends toward hypoglycemic (low blood sugar)

DIET FOR A SLOW METABOLISM

Someone with a slow metabolism will want to implement a slow oxidizer diet and fuel their body with a higher percentage of healthy carbohydrates such as:

  • Vegetables
  • Unrefined whole grains
  • Fruit

Slow oxidizers do best with a small percentage of healthy fats and quality protein in their diet. Lots of vegetables and fruits in their whole form or smoothies are best for slow oxidizers.

Slow oxidizers tend to have difficulty losing weight if too many fats and animal proteins are consumed. The best foods for a slow oxidizer to lose weight include liver cleansing fruits and vegetables.

Slow oxidizers also do great with plant-based protein sources while eating an anti-inflammatory diet high in colorful fruits and vegetables.

If you need help losing think of working with a certified nutrition coach.

Tips for slow oxidizers or carbohydrate types:

  • Emphasize only low fat, lean meats, and only in small amounts with most meals
  • Be careful and selective with dairy intake. Dairy is not for most people.
  • You can easily be addicted to sugar since your body type has the least reaction to it but in the long run it is unhealthy for everyone
  • Make sure to balance carb intake being careful not to eat starchy carbs and starchy vegetables together
  • Since all carbs break down to sugar, be conscious of how many carbs you consume
  • Be careful with grains if they make you tired or sleepy, you may be consuming too much
  • Be careful with gluten and bleached flours, sprouted and whole grains may or may not be tolerable depending on your digestive abilities
  • Eat beans with caution
  • Eat good fats but too much fat slows your metabolism and adds weight
  • If you crave sweets it means you are eating too many carbohydrates
  • Your type requires the least fat, but eat healthy fats and experiment until you find the right amount of intake for you

SIGNS OF A FAST METABOLISM OR FAST OXIDIZER SYMPTOMS INCLUDE:

  • Warm body temperature and does not get cold easily
  • More prone to feeling anxious or wound up
  • Sweats easily
  • Hyperfunction of the adrenal and thyroid glands
  • Rapid transit time
  • Tends toward hyperglycemia (high blood sugar)
  • Weight gain in the abdominal area
  • Craves heavier foods such as fats, animal protein, nuts and seeds
  • Does not feel satiated after eating the lighter hydrating foods such as vegetables and fruits

DIET FOR A FAST METABOLISM

Someone who is a fast oxidizer will want to fuel their bodies with a higher percentage of healthy fats and protein such as:

  • Avocado
  • Nuts and seeds
  • Eggs
  • Quality animal protein

A fast oxidizer does better with a smaller percentage of the diet being unrefined carbohydrates such as vegetables, fruits, grains, and legumes.

The diet that works wonders for your best friend might not be the diet that will work for you if you have different metabolic rates.

Dialing in the macro-nutrient ratios according to your metabolism type will help to provide the necessary satiety and energy levels for your individual needs and metabolic rate.

You can learn more in-depth info on your metabolism type and how to eat for your metabolic type in the Metabolic Typing book.

The mixed oxidizer type:

This type can eat pretty much anything they want if they strike a good balance of nutrients. They get out of balance by leaning more to the fast or slow oxidizer foods so it is important that they keep a balanced intake of both. Many of these types can improve any diabetic issues by staying in balance. They may even switch between fast and slow oxidation as a result of stress or changes in health. Appetite is variable and this type has less of a problem with food cravings or excessive weight gain.

Tips for mixed oxidizers:

  • Read and understand the basics of fast and slow oxidizers
  • Keep food types and amounts in balance for optimum energy
  • Find what works for you and know that your needs may change from day to day
  • Get a good balance and a wide range of proteins
  • Eat some protein at every meal
  • Do not eat the same foods every day
  • Snack when you feel the need to but only foods that give you energy
  • Keep high glycemic foods at a minimum
  • Consume dairy with caution
  • Be cautious with grains, stay away from refined grains
  • Listen to your body when it comes to carbohydrates and know when you are consuming too much

Most foods are tolerable for this type, but again keep amounts in balance.

Metabolic Typing Questionaire

This questionnaire will let you know if you are a fast, slow, or mixed oxidizer. Knowing how you oxidize will help you make the right food choices to lose or gain weight, and improve your health.

1. I am hungry at breakfast
a. Usually
b. No

2. Eating a muffin, cereals, pancakes or other wheat-based foods gives me enough energy to last until lunch
a. Never/Sometimes
b. Usually

3. The meal that best satisfies my hunger at breakfast is

a. Bacon or sausage with eggs

b. Hot or cold cereal, toast, bagel or cereal type bar

c. I have no set breakfast and I can eat a combination of any of the above foods and feel satisfied

4. Eating fruit salad for breakfast or lunch makes me

a. Unsatisfied and still hungry

b. Satisfied

c. Feel okay, but I usually need a snack in between meals

5. Orange juice in the morning does not agree with me

a. True

b. False

6. I often get hungry between meals

a. True

b. False

7. A salad for lunch without meat makes me feel

a. Sleepy or not enough energy

b. Energized and healthy

c. Fine, but a little meat doesn’t hurt.

8. My appetite at dinner is strong

a. True

b. False

9. At dinner, I prefer to have

a. A heavy meal like steak or chicken thighs, with a potato and vegetables to satisfy my hunger.

b. A small amount of fish or chicken breast and salad for dinner to satisfy my hunger

c. I rarely think about food and at times may even forget to eat

10. Heavy food (meat or cheese) before bed interferes with my sleep

a. No, not usually

b. Yes

11. Sweets before bedtime interferes with my sleep

a. Yes

b. No

12. Desserts I prefer are

a. Rich creamy desserts like cheesecake, creamy pastries, ice cream.

b. Fruit pies, cakes, cookies, candy

c. Don’t crave dessert

13. My favorite comfort foods are

a. Salty chips, cheese, peanuts, bread, ice cream, cheesecake

b. Soft drinks, popcorn, fruit

c. None of these.

14. Skipping meals, causes me to feel

a. Shaky, weak, tired, nauseous, or irritable

b. No different

c. It doesn’t really bother me but I feel better when I eat

15. I experience brain fog when I eat

a. Fruits, breads, or sweets

b. Fatty or heavy foods

c. No foods make me feel that way

16. Red meat makes me feel

a. Strong

b. Tired

c. Okay, no problem eating it

17. How do you feel about snacks?

a. I need snacks but prefer foods that satisfy me like meats, cheese, eggs, or nuts

b. I like something sweet when I snack

c. I can snack on anything

18. How is your meat digestion?

a. I digest meat with ease

b. When I eat red meat, I frequently experience GI discomfort, such as gas, bloating or the feeling of being too full

c. When I eat red meat, I have normal digestion, no discomfort

d. I am a vegetarian, I don’t eat meat

19. Vegetarian meals satisfy me completely

a. False

b. True

20. Fatty foods

a. Eating fatty foods such as avocado, seeds, and nut butters make me feel energized

b. Eating fatty foods such as avocado, seeds, and nut butters make me feel lethargic

c. I feel no noticeable difference in energy when I eat fatty foods such as avocado, seeds, and nut butters

21. Fructose Preferences

a. Drinking a glass of juice (without any food) makes me feel jittery, anxious, or nauseous.

b. Drinking a glass of juice (without any food) gives me lasting energy

c. I have no noticeable effects when drinking a glass of juice without any food

22. Salt preferences

a. I crave salt and frequently salt my food

b. I salt my food when needed

c. I don’t crave salty food and I rarely salt my food

23. Personality traits

a. I am often impatient, can be aggressive, and stress easily

b. I am typically patient, laid back, and/or easy going

c. I have average patience

24. I am often

a. Too warm

b. Too chilly

c. Neither/Both

25. I prefer

a. Cool weather

b. Warm or hot weather

c. Does not matter

26. My personality type is

a. Extroverted

b. Introverted, quiet, aloof

c. Not introverted or extroverted

27. My fingernails are

a. Thin and at times brittle

b. Thick and strong

c. Average

28. When insects bite me, my reaction is

a. Quick and strong reaction with swelling

b. Mild

c. Average

29. My body type is

a. Tall, thin, lean, or athletic

b. Short and Stocky

c. Average

30. I often have skin cracks on my fingertips or heels

a. Yes

b. No

31. I am

a. Blood Type O or B

b. Blood Type A or AB

c. Don’t know

Add up the amount of A’s B’s and C’s in your answers. If you picked more A answers you are a fast oxidizer. If you picked more B answers you are a slow oxidizer. If you answered more than 10 C’s you are a mixed oxidizer.


Let me know what you thought of metabolic typing and which type you are 🙂

2 thoughts on “Metabolic Types: Fast, Mixed, and Slow Oxidizers

  1. so I took the metabolic quiz and the result was I am a mixed oxidizer. I am 5′ 8″ and am currently 180lbs. I have actually been monitoring my meals for over a month now eating what I perceived as balanced but my weight just fluctuates between 178 – 180lbs. Are there any tips you can suggest that may help me get off this plateau?

    1. Hey Celeste
      Thank you for the comment.

      There can many factors that influence weight fluctuations. I have many tips and tricks to offer but before I do, I would like to understand your situation a little better so I know how to best assist you. I will email you a follow-up 🙂

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