Recently I’ve read several articles about metabolism, which prompted me to do some more research, which has resulted in this post. I’ve always thought that I have a slow metabolism – i.e. the complete opposite of my husband and all but one of my four brothers – so I’ll take any help I can get!.
Basic definition of metabolism: A chemical process that converts food into energy or stores it as fat.
This is far too simple. When we talk about metabolism, we’re really talking about two different things.
1. Metabolic type
2. Basal metabolic rate
3. Actually, I should throw in a third: Metabolic efficiency
→ Metabolic types
There are three types of metabolisms with three different carb/protein/fat needs. Just to be clear, everyone cannot have the same success with the same nutrient ratios. So, when you see things like, “to lose fat and gain muscle, eat 60% protein 30% carb and 10% fat,” quickly read the other direction.
Fast oxidizers: ideal ratio is 20% carbs, 50% protein, 30% fat.
Slow oxidizers: ideal ratio is 60% carbs, 25% protein, 15% fat.
Balanced oxidizers: ideal ratio is 40% carbs, 30% protein, 30% fat.
“Metabolic typing is really just fancy talk for figuring out how your body processes what you eat—more speciﬁcally, how your body deals with the three basic macronutrients in food: carbohydrates, proteins, and fats,” wrote Jillian Michaels in her book Winning by Losing (Amazon affiliate link). “The fact that we all oxidize the nutrients in our food in different ways is the reason why a particular diet will work for one person and not for another.”
According to Jillian, fast oxidizers burn through nutrients very quickly, meaning glucose is released into the blood almost immediately. This increase in blood sugar triggers the release of insulin, which is stored as fat. Therefore, “foods with high carb ratios cause fatigue and carb cravings as well as promote fat storage.”
Not surprisingly, slow oxidizers are the opposite. They burn through nutrients very slowly which results in delayed energy production. These people should eat a higher ratio of carbs because protein and fat slow oxidization even more.
And finally, balanced oxidizers fall right in the middle. “They require foods that have equal quantities of protein, fat and carbs in order to optimally process, produce and use the energy from their food.”
So how to find out your type?
This About.com article includes a questionnaire from Jillian’s book to determine metabolic type.
Jon and I both did the test and we are both Balanced Oxidizers – lucky us! In fact, our scores are almost identical and are so high that even if we changed some answers, we would still be balance oxidizer.
The tricky part is that our secondary type is opposite (and again, almost the same number score; our respective third type was almost non–existent). Jon’s secondary is Fast Oxidizer while I my second is Slow. This explains why Jon craves protein and I crave carbs. It also makes me feel less annoyed with the carb cravings. My body simply functions better with carbs. Yes, I have this posted on our fridge now, and we’re both thinking about it more as we eat.
Fascinating stuff! Jillian includes a breakdown of what foods are best for each metabolic type after the test, too.
→ Basal Metabolic Rate
This is number of calories burned during regular daily activities. There is a difference between basal metabolic rate (average daily activities) and resting metabolic rate (measures only oxygen input, carbon dioxide output); this isn’t overly important to our general purposes here, though. A proper BMR test has to done by a health professional, but there are some calculators to give an idea.
I like this one from Dummies.com:
BMR Calculation for Women: 655 + (4.35 × weight in pounds) + (4.7 × height in inches) – (4.7 × age in years)
BMR Calculation for Men: 66 + (6.23 × weight in pounds) + (12.7 × height in inches) – (6.76 × age in years)
Factor in exercise: Light (1–3 days), BMR x 1.375. Moderate (3–5 days), BMR x 1.55. Heavy (6–7 days), BMR x 1.725.
According to this equation, my BMR is ~1570 calories per day. Add in exercise, and my range is 2400 – 2700 calories per day. Here are two more online calculators from BodyBuilding.com: Resting metabolic rate and Basal metabolic rate. For me, these spit out ~1400 RMR and ~1900 BMR.
Now, these obviously aren’t the most scientific of calculators, but they do give me a good range of daily caloric intake. When I average the two different BMR’s, I get a goal of about 1700 calories per day, plus my activity. So on a 10–mile–run day when I burn 1000+ calories, I should intake more like 2700 calories to support that training. Sheesh, that’s a lot!
P.S. These numbers are to maintain current weight. Add or subtract to gain or lose weight. (disclaimer here that severely restricting calories isn’t healthy, that I’m not a dietitian and you should work with a doctor/registered dietician/nutritionist).
→ Metabolic efficiency
I’ll make this one quick. ME is “energy intake based on body weight that is required to maintain current weight,” according to Competitor magazine. To wrap my brain around this, I think of it as a combination of, or the result of, my metabolic type and BMR.
In theory, my metabolic efficiency could be low (hence, “I have a slow metabolism”). This means I should either 1) lower the amount of calories I intake from what BMR calculators say, or 2) eat the best balance of nutrients for my metabolic type. Or, more likely, a combination of both.
OK! Hopefully I haven’t lost everyone with this nerdy science-y post! I’m ALL ABOUT understanding my body, how it functions best and ways to support my running addiction. And in reality, I kind of love the nerdy side of health. I think I missed my calling.
• Added bonus: here are a couple of articles about how eating small meals more often does not, in fact, speed up our metabolisms. Via The If Life, Part I & Part II | Via Quick and Dirty Tips, Metabolism Myths.
I didn’t go into that in the post, and I’m not sure how convinced I am either way, but I thought this was worth including. For me, my main take–a–way is finding what works for your body.