An Ideal Body Weight Is Probably Lower Than You Think

Weight is one of the most talked about topics today. The perception of an “ideal” body weight (IBW), is often based on what is promoted through the media. TV, movies, magazines, advertisements have us chasing after a weight that is only based on the perception of what a desirable weight is. This perception has changed considerably over the last century.

But there is a less frivolous side to a desirable weight. The notion of an ideal body weight (IBW) was originally introduced to estimate dosages for medical use, where the metabolism of certain drugs is more based on IBW than it is on total body weight. Insurance company actuaries then refined its use to estimate life expectancy for life insurance policies. Today, IBW is widely used in medicine, healthy weight recommendations, and throughout sports.

A person’s weight is highly individual and not an exact science.  There is no measure that can definitively state how much a person should weigh to be healthy and it’s much more important to make healthy life choices such as regular exercise, eating a variety of healthy foods, getting enough sleep, and reducing stress.

Having said that, it is still useful to find a recommendation on an ideal body weight that is based on available data.

The gold standard today for measuring “normal” body weight is the BMI Index. This is the calculation promoted by the WHO.

However,  when I plug my height into this equation, the first thing that I notice is the size of the range. The BMI index is showing a normal healthy weight range of 20 kg. Really? My weight can go up or down by 20 kg and still be normal.

I’ve been tracking my weight with some health biomarkers, such as cholesterol and blood pressure for years. From these observations, for myself at least, I have found the BMI index to be very misleading. My biomarkers only start moving into their normal range at a weight below 78.8 kg, which is about four kilograms lower than where the BMI index is telling me that I am at a normal healthy weight. But it is not until my weight drops below 76.5 kg, that all the tracked biomarkers come into the normal healthy range, which is a full six kilogram below the BMI recommendation. 

My healthy body weight is below 76.5 kg, which is six kilograms (13 lbs in the US or over a stone in the UK) lower than the upper bound of what the WHO’s BMI index gives as a normal weight range.

Needless to say, I have lost confidence in the BMI index as a measure of a healthy weight. It probably has a place in classifying obesity in large population samples, but from my experience it is not useful for calculating an individual’s healthy weight.

This led me to researching other models and formulae that would fit with my recorded observations.

The following table lists the main formulas and tables used to estimate ideal body weights and weight ranges. Estimates of an ideal body weight, for a six foot male of medium build are also included for comparison purposes

FormulaCommentSample Weight*
Metropolitan Life Height-Weight Tables 1943, Revised 1983In 1943, the Metropolitan Life Insurance Company introduced their standard height-weight tables, which would indicate those persons with the lowest mortality rates70.0-76.3 kg
G. J. Hamwi Formula, 1964Invented for medicinal dosage purposes.
80.0 kg
B. J. Devine Formula (1974)Originally intended as a basis for medicinal dosages. The formula is now universally used for Ideal Body Weight.
77.0 kg
J. D. Robinson Formula (1983)
Modification of the Devine Formula.74 .3 kg
D. R. Miller Formula (1983)Modification of the Devine Formula.72.7 kg
Harry J. M. Lemmens Formula (2005)This formula is an improvement on the other formulae. The formula is: Ideal Body Weight (kg) = 22 x height^2 (meter)73.0 kg
Healthy BMI RangeBMI is currently the official metric for classifying individuals according to different obesity levels.
62.0 - 83.0 kgs
*Comparison result for a six foot male of medium build.

There are limitations to all these formulas and methods, so picking a formula is a bit like sticking a finger in the air. However, I wanted to place my selection on a more scientific footing, based on my empirical observations of comparing my weight with tracked biomarkers, such as cholesterol and blood pressure.

Using my own height, I compared the estimated body weights, which I’ve summarized in the chart below:

As you can see the BMI index is pretty broad. Perhaps too broad. When I plug in my healthy biomarkers on the chart, the BMI healthy range is not healthy at all at its upper limits of normal. However being so broad it includes other models that appear more accurate. Perhaps the BMI healthy range needs to be narrowed somewhat.

The most commonly used formula today in medicine and for calculating an ideal body weight is the Devine formula, but as can be seen from the chart above, it also calculates an ideal body weight that is above the range of the healthy biomarkers.

Perhaps as the western world’s weight increases, so does the ideal body weight formulas. If the formulas are based on current population averages, then this might be expected, but that doesn’t necessarily mean they are healthy averages.

However, if we go back seventy-five years we find something different. We find a population with very little obesity and now we can find ideal body weights within a population of people that are already at a healthier weight. 

As far back as 1943, we find height-weight tables that match my own biomarker observations. In 1943, the Metropolitan Life Insurance Company introduced their standard height-weight tables for men and women. The tables were revised slightly in 1983. They indicate those persons with the lowest mortality rates. It is interesting to note that these statistics were produced for profit incentives by the insurance industry trying to find people with the lowest mortality rates to offer life insurance policies.

It is interesting to note that the midpoint of this range closely matches the ideal body weight formulas used by Miller, from 1983, and Lemmen, from 2005.

As the Lemmen formula is the most recent while still concurring with the old Metropolitan Life tables, this is the formula that I use for calculating an ideal body weight.

To calculate an ideal body weight range, I take a range that is 4.5% above and below the IBW, as this range closely matches the Metropolitan Life tables. This gives an ideal body range that can be easily calculated from the lemmen formula, while being very close to and within the range of the Metropolitan tables. In this case the healthy range is much narrower at about six kilograms compared to the unrealistically large 20 kg normal healthy range given by the BMI Index.

I’ve coded the ideal body weight together with the ideal body weight range into the calculator below.

How does weight affect Activities?

There is no question that shedding a few extra kilos will make most weight-bearing activities more enjoyable while also improving performance and minimizing injury.

Healthy runners will race about 2.75 seconds a  kilometre faster over a marathon distance for every kilogram that they lose. 

Losing excess weight is also good for your Knees.

According to a study on knee impact forces by Ross Miller, Ph.D., every step you walk causes a load on your knee that is 2 to 3 times your body weight. 

So for each kilogram that you lose, you will reduce the impact forces on your knee by around 2-3 kg.

According to Miller, the accumulated forces on the knee over a given distance is the same whether walking or running. 

These forces increase when running by between 5 to 12 times your body weight, but as your foot is on the ground half the length of time when running compared to walking (30% vs 60% of time) , the accumulated forces are the same.

From my own experience, I have noticed a considerable difference when mountain running at a weight of 76 kg and at 77 kg. At 76 kg, I feel really light and springy on my feet when running on technical terrain compared to the plodding sensation when only a mere kilogram heavier.

A lighter body weight makes for more enjoyable Mountain Running

For me, being within my ideal Body weight range at 76.0 kg, has a noticeable improvement on both my health, running form and performance.

Running becomes more like a floating or bouncing experience. A type of active meditation, like Yoga.

Typical weights of endurance athletes

It is interesting to compare this IBW calculation with the weights of endurance athletes as an aspirational exercise.

AthleteSportHeightWeightBMIBMI=22 Diff*
James WilksMixed Martial Arts and producer of the Game Changers.185 cm77 kg22.5+1.7 kg
Scott JurekLegendary Ultrarunner who set course records on many events.188 cm77 kg21.8-0.8 kg
Jim WalsmleyUltrarunner who won the JFK 50 Mile three years Inna row.182 cm70 kg21.1-2.9 kg
Sage CanadayUltrarunner who won the USATF 100K Trail Championship; Speedgoat 50k; Lake Sonoma 50.180 cm68 kg21.0-3.3 kg
Yassine DibounUltrarunner who won Leona Divide 50k.180.3 cm68 kg 21.0-3.5 kg
*BMI=22 Diff: Weight above (+) or below (-) an ideal BMI of 22 (22 is commonly used as BMI and coincides with the Ideal Body Weight Calculations discussed here)

We notice that athletes, at the top of their game have a weight close to the healthy IBW range shown above. The above athletes also follow a high carbohydrate vegetarian or vegan diet comprised mainly of healthy whole foods.

A Prioritize Lifestyle

A healthy lifestyle takes effort but it’s a worthwhile one, that fits well with a minimalist philosophy of intentional living.

People often can achieve great things that have the power to impress their peers, but if that effort is wasted on acquiring consumables and being a slave to a fashion industry then its quite sad and misguided.

When you are at a healthy weight, everything looks good on you, allowing you to really simplify your wardrobe to a few items like a pair of jeans and a couple of t-shirts. You don’t need to waste time thinking about fashion or colours. A healthy weight allows you to enjoy healthy active pastimes, like running and hiking that cost virtually nothing.

A minimalist lifestyle is not just about getting rid of things, it’s about prioritizing the important things in your life, like people, health and authentic aspirations.

What does Hypothermia feel like

It’s a warm day, not a cloud in the sky. It’s the month of March on a isolated mountain in Ireland and the weather has been uncharacteristically warm for this time of the year. There is so much heat from the sun that you leave you warm clothes behind and don’t bring any food with you. It’s a warm day you’ll be up and down in no time.
After a four hour trek up to one of the summits, you spot a rocky outcrop that you decide will be a fun scramble. The is a beautiful scramble, just one little crux that you need to get across. A quick jump on to protruding foothold and you extend your hand to grab a very obvious handhold. As you switch balance and reach, the foothold snaps. The next thing you realise is that you are falling. You manage to land on your feet when you hear a snap. You try to stand up but pain shoots through your right ankle.
You are now immobilised alone on the top of a mountain. You sit on a rock berating yourself for being so stupid.
Sitting there you notice that it’s actually quite cold when you’re not moving. Searching through your small backpack for anything, you find nothing but your phone and a small bottle of Rum.
Hypothermia occurs when the body is unable to maintain normal temperatures because of exposure to cold. The body’s normal core temperature is between 36.5°C and 37.5°C.
Hyperthermia affects Hikers and armies alike.
The classical piece by Tchaikovsky, the 1812 Overture, commemorates the successful Russian defence against Napoleon’s invading army.

Hypothermia aided the destruction of the invading army by causing confusion, lost of consciousness and death. Others just fell to their knees and eventually died where they knelt.
As hikers, we may not be braving the severe Russian winters, but we are equally at risk of hypothermia. We are particularly at risk when temperatures are around freezing. Even in warmer temperature we can still be at risk. Simply being immobile on a mountain ridge at 10 °C in a storm can kill you. Windchill makes it worse by moving the warm air next to your skin away. Wet makes it worse. Water evaporates and cools. It also reduces the effectiveness of insulation. The combination is deadly. Skinny people are more susceptible than overweight people.
Not sure what to do, feeling the pain of the broken ankle, hoping someone will pass by, you decide to warm up by taking a couple swigs of rum. You now feel much warmer and more relaxed.
However, alcohol consumption increases the risk of hypothermia by increasing blood flow to the skin, resulting in heat being lost to the environment. This produces the effect of you feeling warm, when you are actually losing heat. Alcohol can also decrease the body’s ability to shiver and use energy that would normally aid the body in generating heat. The overall effects of alcohol leads to a decrease in body temperature and a decreased ability to generate body heat in response to cold environments.
The earliest stages, called mild hypothermia, are characterized by such things as a loss of coordination and changes in personality.
As the sun drops behind a far away peak, the temperatures plummets to around 7°C. You are feeling very cold and you’re core body temperature now drops below 34 °C, you now start to shiver. At this point, you still have the presence of mind to do things like make a phone call. You can temporarily stop the shivering to retrieve the phone and dial a number. But there is no reception, there are no network antennas in close proximity to even allow an emergency call.
As your temperature continues to fall below 34 °C, the shivering becomes uncontrollable.
The evening progress and you feel the cold. As you core body temperature falls to 32 °C, you are now having irrational thoughts, sluggish thinking, amnesia, and difficulty speaking. You know you are in a perilous situation, but you are feeling surprisingly calm. You have no real dread or any real pain or distress. Without that fear of death, the drive to take care of oneself is lost. At this point you know you should be doing something to save yourself but you can’t really be bothered.
As your body temperature drops below 32 °C,  you stop shivering. Now you feel really confused and start behaving more irrationally.
Once  shivering ceases you are in a life threatening situation and will very likely die if you do not get help.
Parts of your body will start to shut down, sending messages to the brain telling it that these areas are fine. Your brain doesn’t care anymore or simply doesn’t know that it’s cold.
You start to experience a behaviour called paradoxical undressing. You become disoriented, confused, and combative. You feel like your skin is too hot and burning and so start discarding your clothing, which, in turn, increases your rate of heat loss.
In severe hypothermia you can be quite serene, not frightened, or not even really alarmed. You know you are in trouble, but you have resigned yourself to it and are pretty calm.
You have been sitting here immobilised for several hours now while staring at a clear dark sky and the ambient temperature has now fallen to freezing.
Suddenly you hear a voice. Yes, it’s your friend, he’s calling. At last, and unbelievably, his hut is just 50 metres away hidden behind a boulder. Your friend helps you up and you now see his house, which is fully lit up. Opening the door, you are welcomed by a blazing open fire, your friend lays you down on a thick soft rug in front of the open fire. You begin to warm up and feel a great sense of relief and gratitude that the ordeal is over. The hut is beautifully decorated inside. Your friend is preparing a pasta dish and there is an opened bottle of red wine on the table. This was some ordeal but you sure will have some story to tell tomorrow. In the meantime you will need to get your ankle seen to and will have to make you way from your friends hut to your home. But those things can be taken care of tomorrow. Tonight, you are getting heat back into your body and are about to feast on a meal with wine.
The flames from the fire dance around the wood and then start changing form, the flames darken and get smaller, the interior of the hut starts to vanish. You call to your friend to ask what’s happening, suddenly you are alone staring at an empty sky.
With restricted blood flow to the brain, you have started to hallucinate. Your friend, the hut, the meal, the wine were only a illusions. You now become consumed with a sense of despondency of dying alone on the side of a mountain. Tears roll down your cheeks.
The despondency lasts for a while and then is replaced with a calm acceptance of your fate.
With your core body temperature below 29 °C,  you become unconscious. As the brain cools down, you experience a gradual decrease in your level of consciousness until you slip into a coma. After that, all of your metabolic processes start to slow down. As your body temperature drops below 26 °C, your heartbeat will become irregular and eventually stop. The moment of death will likely be silent and relatively painless.
A person dying from hypothermia will get into sort of a dreamlike state, drifting in and out of consciousness, and they may have visions of random things, possibly in a state of bliss. Dying from hypothermia is often perceived as a slow and painful death. It may be slow but by all accounts it’s not as painful as people believe.
The next day a walker finds your dead body and your death becomes another lesson and another statistic on how to dress for the outdoors.

This hypothetical account of hypothermia is based on my own experiences of mild hypothermia together with the research that I have done into the matter.