Reader Request – Metabolic Age

Question: What is my metabolic age, and should I be concerned about it?

Response: Thank you for the question! This morning, I found a website that calculated my metabolic age for me after I answered some questions about my age/height/weight, and then a couple lifestyle questions (perceived sleep quality, stress, eating habits). Without any visibility into the calculation process, the website (after entering my email address, of course) told me my metabolic age is 37. Exactly 1 year less than my biological age.

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Hooray. I’m stoked. But, not really…

For the purposes of tracking body fat % trends, I use a scale from a company called Renpho. They claim the numbers are benchmarked against more exact measurements and calibrated before leaving the factory. So, the error compared against, say for instance, a BodPod analysis, should be relatively small. When it comes to stuff like that, I’m okay if the number is a little off from reality – just as long as its off by the same factor each time. If it is, then the TREND DATA will tell me all I need to know. Anyway, the Renpho app gives me a “metabolic age” number as well. As of my last measurement, it was 39. Exactly 1 year OLDER than my actual age.

Hmmm – two sources, two different numbers. One good, one bad.


Bummer. I’m sad. But, not really.

After scouring the Internet for the better part of the morning, I couldn’t find an actual formula or algorithm (public anyway) that allows you to do the calculation on your own. I did find this “definition (source article linked)” of metabolic age from (and it was corroborated by a couple other sites) – “Metabolic age is a comparison between a person’s basal metabolic rate (BMR) against the average BMR for an age. (”.

Okay – so that means if I calculate my personal BMR, and compare it against the average BMR for my age group, I’ll know how I stand. In other words, if my BMR says that I have the same metabolism as a 32 year old, then I’m metabolically 32, even though I’m biologically 38. Conversely, if the comparison says my metabolic rate is the same as a 44 year old, and I’m only biologically 38, then I’m metabolically older than I am biologically.

I guess the conclusion to draw is – if you are metabolically younger than your biological age, it’s a good thing. Easy enough – I’ll just make myself metabolically younger. Hold on – not so fast.

But what does that all actually mean, and is it useful, actionable data? If the bedrock of this analysis is the BMR, I’d say NO for three reasons.

First, the generally used formula for computing a person’s BMR is the Harris-Benedict formula. The formula is…

  • Women = 655 + (4.35 x weight in lbs) + (4.7 x height in inches) – (4.7 x age in years)
  • Men = 66 + (6.23 x weight in lbs) + (12.7 x height in inches) – (6.8 x age in years)

My problem with using this number to draw a conclusion about overall health is the fact that the only controllable variable in the equation for a person is their weight. As I’ve stated in other posts, weight can be a very false idol for evaluating your health. It is very possible to have a large amount of muscle, low to medium body fat, and be considered overweight according to the BMI (body mass index – ratio of weight to height) scale. My own BMI runs around 27.2. That puts me in the high/overweight category. But, with a body fat % between 10% and 15% (depending on the measuring tool used), I’m certainly not overweight. My point is that body weight alone isn’t a good metric to determine if you need to make a change. Body weight itself is a number based on a bunch of different variables – muscle/bone mass, water retention, and body fat to name a few. People at the extreme ends of the spectrum can probably make a blanket assumption about their condition (needing to gain weight or lose weight). But, the people in the middle really need to understand what numbers are driving their body weight. If a person has relatively low body fat and moderate to high muscle mass, there is probably no reason for them to try and lose weight, no matter what the scale tells them.

Second, the Harris-Benedict formula was shown to have some deficiencies in estimating/predicting energy requirements.

If the formula used to calculate the BMR, which is then used to calculate your metabolic age, has some limitations, then how reliable is the derivative number? How actionable is a number (based on a number) that may or may not be reliable/accurate?

Third, try to find a chart that maps out the BMR for age groups. Then, try to find a chart that maps out the IDEAL BMR for age groups. Go ahead – I’ll wait…

I couldn’t find one, and neither could some other websites that expressed a similar frustration. If you can’t find and scrutinize the benchmark, how good is your analysis going to be?

I agree that having metrics to measure elements of our health is a great thing, and people should do it as much as they can. Peter Drucker (a very famous management thinker) says, “You can’t manage what you can’t measure.” The corollary thought would be – if you measure it, you can manage it. However, if you track ambiguous metrics or even worse, incorrect metrics, you’ll have a “garbage in-garbage out” analysis situation. When deciding if a data point is worth tracking ask yourself if it is actionable.

In other words, does knowing that number allow you to zero in on specific action to affect it?

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Metrics like weight, BMI, and metabolic age have multiple inputs that affect the resulting number. You could reduce your weight by reducing muscle mass, reducing water mass, reducing bone mass, or reducing fat mass. Only one of those four is probably a desired option (assuming you have excess body fat). In that case your better bet is to track and try to affect your body fat % number. Sure, the weight, BMI, and metabolic age will come along for the ride, but it is the tracking and action on one variable that makes the impact.

So, in my opinion, metabolic age probably isn’t the best metric to help you formulate an action plan. All it is really telling you (based on its use of BMR) is that you might need to lose weight. I’d say your time is better spent trying to measure and track trends on something a little less ambiguous.



Reader Request – Recovery Strategies

Reader question:

Can you provide information on how to recover from a brutal workout in terms of food, stretches, hot/cold therapy, etc…


Thanks for asking the question! Recovery should be a big part of your overall fitness and nutrition plan. If you are just killing yourself during workouts, and not doing anything to support that work leading up to your next killer workout, not only are you leaving progress on the table, you are setting yourself up for potential injury.

I will note that there is no magic bullet for eliminating muscle soreness in a new workout routine. The phenomenon of delayed onset muscle soreness (DOMS) is a result of metabolic stress from the workout, and you can’t really prevent it. Your body will adapt as you keep doing the load that caused the DOMS, and it will lessen/leave as time goes on. If you follow the principle of progressive overload and give yourself time to adapt to the work, you’ll minimize soreness. If you go completely banana sandwich crazy in your first workout, good luck moving the next day.

I’ll do my best to unpack some of the basic ideas that will allow you to formulate a good recovery plan.

Hydration – being properly hydrated is one of the most important things you can do, not only for recovery, but for general well-being. Your body, when properly hydrated, is about 65% water (and your muscles are about 75% water). I won’t go into painful detail about all of the benefits of staying hydrated (there is plenty of information about that out there), but at minimum, you should aim to replenish what you lost during the exercise session. Losing even 1% of your body’s water weight can affect performance & recovery. Post-workout, your muscles need to be properly hydrated as part of the repair process (protein synthesis). If you are dehydrated, the protein synthesis doesn’t happen properly, and repair is stunted. In terms of digestion, proper levels of hydration allow your post-workout snack/meal to be digested more effectively (which leads to better nutrient absorption). So, step 1 – DRINK LOTS OF WATER. In terms of how much, lean more towards 1 ounce of water per pound of body weight – not necessarily the eight 8-ounce glasses we’ve been told since we were kids.

Food – post workout eating can not only aid with gains, but also aid with recovery. During your workout, you are actually causing micro tears to your muscles. These tears are the result of repeated muscle contractions, and are known as “microtrauma.” This is a good thing. It signals that a repair has to happen. If you recover properly, the muscle will be repaired to handle a progressively larger workload the next time around. In the couple hours post workout, the receptors around your muscle are fiending for glucose (from carbohydrates) and amino acids (from protein). These nutrients allow the repair process to move along. If you eat a snack (or meal) that has protein in it (aim for 20 grams or more), you’ll be doing your muscles a huge favor by helping to buoy the rebuilding process. So, step 2 – EAT SOMETHING WITH PROTEIN IN IT! For example – I just finished a workout, and refueled with the following:

  • Bowl full of spring mix
  • 1 – 4 oz chicken breast diced up
  • 2 cups broccoli
  • 1/4 cup of homemade salad dressing (avocado oil, extra virgin olive oil, balsamic vinegar, apple cider vinegar, dijon mustard)

Bottom line – just eat something from your overall nutrition plan that has protein in it. You don’t need to spend tons of money on supplements, BUT, I will say that having a good clean protein powder in your pantry isn’t a bad idea. If I’m not ready to eat a full-fledged meal, and I need a quick post-workout boost, I’ll do a protein shake smoothie like this…

  • 8 oz unsweetened almond or coconut milk
  • 8 oz water
  • 2 heaping tablespoons of full fat greek yogurt
  • 1 scoop NutriBio unflavored whey protein
  • 1/2 cup frozen blueberries
  • 1 tsp 100% cacao powder

It’s simple and to the point – it gets me my protein, and tastes yummy (the blueberries and cacao are for the antioxidants). I picked that protein powder specifically after a long and exhaustive search because it’s clean – no junk, no additives – just 100% whey protein isolate. Be careful with commercial protein powders – they are so full of garbage a lot of the times.

If I were in a pinch, I’d grab either a Rise Bar (banana flavor is my favorite) or an Epic Bar (Bison is awesome). They aren’t 20 grams of protein, but they are a good go-to when you are on the move. I keep my desk drawer and business bag stocked with them at all times. Throw in a handful of almonds or macadamia nuts, and I’m sound as a pound.

Mobility/flexibility/programming – This is where people usually err, and it costs them. In my opinion, a good exercise protocol consists of:

  1. Dynamic warmup
  2. Strength skill training
  3. Metabolic and/or heart rate circuit
  4. Easy dynamic stretch cool down
  5. *programmed flexibility/mobility training on non-strength days
  6. *programmed rest days to allow full recovery to the muscle group

For the purposes of recovery, I think 1 & 4, 5, and 6 are key. Before that, a quick note on programming (if you write your own exercise programs). Muscle is torn down when you exercise, and rebuilds when you rest. I’ll say that again – YOU DO NOT BUILD MUSCLE AT THE GYM. You MUST HAVE PROGRAMMED REST for areas you are hitting hard. At minimum, you should consider 24-48 hours before you attack the same muscle group again. It is very possible to see strength gains by only doing a strength workout for a body part/group one day a week. It will take you longer to reach your goals, but it’s possible. If you are looking to fast track your gains, you want to re-engage the muscle group again as quickly as possible after its fully recovered. That is why people will train the same muscle group a couple times per week. What you don’t want to do is nail the same muscle group before its fully recovered. That is counter-productive and an overall waste of your time.

Dynamic warm ups lube up the body and joints by not only getting your heart rate elevated, but by also getting the synovial fluid in your joints pumping.  I always aim to create a mini circuit of dynamic movements for about 3-5 minutes. It could even be as simple as jump roping for 3-5 minutes. Heck – do a mixture of jumping jacks skills for 3-5 minutes. The key is to lube up the body by moving across multiple planes (vertical, horizontal, transverse). Here is a favorite of mine – 30 seconds each:

  1. side rotation
  2. overhead squat
  3. overhead side bend
  4. reverse lunge with twist over front leg
  5. world’s greatest stretch (named by Tony Horton)
  6. scorpion twists
  7. soldier kicks
  8. side leg raises

The dynamic stretch and cool down period (though low in intensity) is important also. Believe it or not, this isn’t to reduce soreness. Studies have shown that post-exercise stretching (right after) did not reduce delayed onset muscle soreness (DOMS). Contrary to popular belief, you are not increasing blood flow to the muscles either. This is mostly to let the heart rate come down. Some favorites include:

  • light jog
  • alternating knee pulls
  • flappy arm hugs
  • side to side lunges
  • beat your boots

Again – the above should be LOW intensity – just keep moving while your heart rate is coming down.

You should not do intense static stretching following an intense workout session. You should program separate days for intense stretching and mobility training. If you think that static stretching cures all ills, here is a very interesting article about how static stretching post workout could be a wolf in sheep’s clothes. So, step 3, HAVE A GOOD WARMUP AND COOLDOWN, AND GIVE YOURSELF PROPER REST BETWEEN STRENGTH SESSIONS.

Programmed mobility & flexibility training – in my opinion and experience, you should dedicate at least 1 session per week to some type of mobility/flexibility training, AND include foam rolling as part of the process. Aside from hot/cold therapies, foam rolling can reduce adhesions and increase blood flow to the muscles. In terms of mobility/flexibility training, you can’t go wrong with either yoga or pilates. Therefore, STEP 4 – TRAIN MOBILITY ON SEPARATE DAYS AND GET A FOAM ROLLER! Quick note about foam rolling – you can do it any time you want. In my experience, the more you do it, the better your muscles feel.

Heat/cold therapy – I’ll be quick on this one – don’t use ice for muscle soreness related to injury. Cold therapy should be reserved for reducing inflammation due to INJURY. Don’t consider DOMS to be an injury. I’m aware that cryo-tanks are a big rage right now, but, to date, there isn’t a lot of scientific evidence to support claims of eliminating muscle soreness. To help the recovery process due to exercise related metabolic stress, your best shot will be heat. It will increase blood flow to the area, and will overall aid/speed recovery. If you don’t want to believe me – check out this doctor’s article. STEP 5 – DON’T ICE YOUR SORE MUSCLES.

Sleep – And finally, STEP 6 – GET PLENTY OF QUALITY SLEEP! Rather than paraphrase, I’m just going to link to a great article on why you need sleep.