Couch to 5K
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The Truth About Weight Loss (Fat Loss)

In my last (stunningly well-read) blog, I started a series on how to get good information about nutrition, exercise and weight loss. Chapter 1 dealt mostly with how to decide for yourself if a "scientific" claim is probably valid and useful, so that you can make good choices for yourself, when there is soooo much conflicting information out there. ( )

This is Chapter 2A: Weight Loss (Fat Loss)

Before I talk at all about how to lose weight, I want to clarify. What I really mean is, how to lose FAT. When dieting, it is also possible (even probable) to lose lean body mass, including muscle. This is not really the goal. Aside from helping you do things like walk, brush your teeth and type on the computer, muscle is important for a) running and b) losing more fat. I will not get further into that for this chapter - that is another chapter on its own. Suffice it to say - you may not be in your ideal body yet. To get closer, you should aim to lose fat and keep your muscle. (Yes, even if you are a woman who is naturally muscular. Trust me.)

Scales do not measure fat vs. lean. In fact, the easiest way to lose weight is to take your scale up a mountain, and weigh yourself there (less gravity). Or in a swimming pool (buoyancy). Weight is just the amount of pressure you put on the scale's pressure plate. So using the scale as your primary means of measuring progress towards health is tracking the wrong thing.

What is the right thing to measure? A very good question, with a few answers.

1) Body fat percentage is the actual measure of how fat you are. You need a certain amount of fat to stay alive, so it isn't the enemy. You just want to aim for a healthy body composition. Here is a chart based on age and gender: Depending on your age, women should aim for 20-30% and men should aim for about 10-20%.

How to measure this right thing:

The most accurate tools are a DEXA scan or a water-immersion test. These are very accurate, but very expensive and difficult to do. Bio-electrical impedance is another method; a very low electrical charge is sent through the body and timed. Fat is less conductive than lean mass, so the faster it goes, the leaner you are. The accuracy of these tests varies a great deal by the instrument, but it is fairly cheap, fast and painless, and can be self-administered. Skin-fold calipers are low-tech, low-cost and accurate when used correctly, but require another person to measure you, and that person needs to be able to do it precisely and with the right technique. A tape measure is extremely cheap and simple to use. It is best when done by another person, even so. And the results can be considerably more variable if you are not consistent with the snugness of the tape measure, or if you use a body fat calculator with your measurements that does not fit your body type. The least accurate, but still useful measure: your jeans and a mirror. If your clothes are getting looser, and you see more muscles, you are losing fat and probably not too much lean mass.

This is why people, even doctors, like scales. They are easy. They are concrete. A number flashes up at you and bada-bing you have your measurement. Is it less than before? Good!

But there is a way: You can still use any method with a fair degree of usefulness if you *track it over time*. You can measure yourself with a tape measure every week and write it down, and even if your calculator is inaccurate, and you yourself make mistakes with the measurements, you will still see a trend over time. Your estimated Body Fat percentage could be off by 10% (a huge margin) and still be useful if it is always 10% high, because you can see if it is going up or down.

Personally, I use a bioelectrical impedance scale. It was expensive, for a bathroom scale, but not terrible (about $60). I can then track my weight in total, my lean mass and my body fat, all by myself. I also use a tape measure to track if I am shrinking, and where. If I put my tape measurements into various online body fat calculators, the answer doesn't match my scale's measurement of body fat, but the trend over time for both is that I am losing mostly fat, and limited lean body mass. I would also be a strong proponent of the skin-fold caliper method over time, if you have a friend to help you. They are inexpensive. ($15 for the calipers. Friends, of course, are priceless.)

2) What about BMI? Isn't that the right thing to measure too? Sort of. Body Mass Index (BMI) is a mathematical formula that only has two variables: height and weight. It is therefore a glorified height-weight chart, designed so the BMI number means the same thing at every height and gender. (Healthy is 18.5-25, Overweight is 25-30, Obese is 30+) It has the exact same limitations as your scale does - namely it doesn't specify how much of your body is fat or lean or anything else.

That said, BMI is such an easy metric, that a lot of "good science" (see my previous post) studies have been done using it. There have been strong correlations found between having a higher BMI and having all kinds of illnesses: high blood pressure, joint problems, heart problems, diabetes, mortality, you name it. Not to mention having your jeans fit too tightly.

What does this mean exactly? Let's look at one example: using a whole bunch of test subjects, researchers found men with diabetes had obesity as an underlying problem in 64% of cases. Directly this means that a lot of men with diabetes had a BMI of over 30. Since those tests were not comparing body fat percentage with diabetes, we can even consider that some of those "obese" diabetic men probably did not have as much body fat as others. So we can conclude that regardless of body fat percentage, there is a greater likelihood to be obese if you are a man with Type II Diabetes. Although this particular reference does not state it, it is also accurate to conclude - from similar research - that being obese (having a BMI over 30) makes getting diabetes more likely. (

You still with me? To put it simply, all these tests studying BMI rather than body fat percentage, still show increased risk of disease at higher weights (regardless of how fat or lean you are). So if your BMI is higher (or lower) than it should be, even if you are in good shape, it is worth confirming with your doctor that you personally are not at increased risk. Note: I have heard some criticism that research using BMI as a metric over-emphasizes the risk to individuals who have a healthy body composition, but are still heavy (big bones, lots of muscle). That may well be true, but like we discussed before, it isn't "good science" if it isn't properly studied and documented, and I haven't seen the evidence yet. (Have you? Do you have a link? I am interested if you come across something like that.)

***Note on BMI and children: The challenges with BMI (being a height/weight chart and not a body fat measurement) are even greater for children. Girls and boys differ, and everyone grows at different rates and times in their lives. To attempt to account for this, BMI charts for children are based upon percentiles, the 5th to 85th percentile being "healthy" and greater than that being probably overweight or obese. One of the biggest problems is when people use this reading as the actual determination of whether a child is too heavy. It is meant to be an indicator that more testing is needed to determine body fat percentage. Poor understanding of the tool, and stigmatizing a child who is healthy but muscular can lead to understandable criticism. It is important to remember that especially for children, BMI is just a first screen, not the final diagnosis. ( )

3) What about types of fat or how it sits on my body? I keep hearing about "belly fat" being bad. What is that all about?

There are actually a few types of fat in our bodies. They include intramuscular fat (marbled in your muscles), subcutaneous fat (right under the skin), and visceral fat (tucked in around your viscera - internal organs in the abdomen, aka belly fat). Fat in our bodies generates hormones which affect (among other things) our appetite, metabolism and insulin sensitivity. Subcutaneous fat and intramuscular fat create these hormones, but are not found to be as dangerous as excess visceral fat, where the hormones go directly into the internal organs and can wreak havoc.

So how do you know what kind of fat you have? It's pretty easy, actually. Fat on your arms, hips, thighs, bum, and so forth are subcutaneous fat, with possibly some intramuscular fat. Fat around the belly, especially if it is a pot-belly kind of situation, is the dangerous visceral fat. Taking measurements of your waist (at the narrowest point for women, the navel for men) and aiming to keep that smaller than half your height is a very good start. Example, a 5'0 person is 60 inches tall. Her waist should be under 30 inches. A 6'0 man is 72 inches tall, and should have a waist under 36 inches. This is the upper limit for a healthy belly size, definitely go for smaller if you can.

This is just as important as monitoring your total body fat and your BMI, because excess visceral fat (even if you are slim and toned everywhere else on your body) is strongly correlated with all those nasty diseases we talked about earlier: diabetes, heart problems, and so on.

4) What else do I measure? There are so many to choose from. Pay attention to anything that you personally suffer from, that your close family has, or that your doctor says is important. Is your cholesterol and blood pressure in a good place? Is your resting heart rate going down or staying low? All these things are good indications that you are getting healthier and taking good/better care of yourself.

***"Ok. Riiiiight. But How Do I Lose Weight, Errrr I Mean Fat?" I want to be size X and fit into the jeans in the back of my closet.

Here's how: do a bunch of the behaviors strongly correlated with Fat Loss. I will discuss them in the next post, very soon.

23 Replies

I use a scale like yours, but I don't go the extra step and take my measurements. My main indicator that I am shrinking is that my clothes are too large now. I just recently had to buy a new wardrobe for a new job (I haven't worked since last year, and had gotten too big for my clothes before I started my lifestyle change in April), and have gone down 2 sizes. I am not going to hang out to my old clothes for memories or "just in case". They are boxed up, and ready to be dropped off at Goodwill.

I know you've not discussed it yet, but I do wonder how I will be able to increase my calorie intake after I reach a weight that I want to maintain, but I get more than ample volumes of food with my current 1,200 calorie eating plan. I do have request for you. Please discuss visceral and subcutaneous fat, and the potential health hazards of belly fat in your post about weight loss.

Some people may have noticed that I said eating plan, and not diet, because what I eat is intentionally consumed. Diets are for temporary attempts to solve an eating problem.


First off, congrats on shrinking 2 sizes and getting a new job! It sounds like life is turning onto a fantastic path for you. Thank you for the suggestion about visceral vs subcutaneous fat. I think I will amend this post to include some information about it - it seems to fit here.

And just in case I don't address it in later posts: as you lose weight, your total caloric needs will probably go down, unless you increase your activity, so you may not need to increase your intake that much. When you get to your goal weight, start adding perhaps 100-250 cal/day for a week or two and see if that stabilizes you. If not, add another 100-250 cal/day and check again. If you are eating normal food already (not just weight loss shakes or whatever), and you feel full, you can add a slightly more energy-dense food, such as replacing egg-whites with whole eggs, or having an extra slice of bread, or another piece of fruit. Another way to sneak in extra calories if you feel full already is to have an extra smack/mini-meal. Heck, if you already have a really well-balanced diet, you could add a reasonable treat as part of your maintenance plan. If you need more info, we can message each other directly. :)


This blog is fasinating, I would love to share this information with all my friends on would you mind if I copied it and further blogs across to them Alaiyo?


I am delighted by the idea of having more people get to read, and hopefully enjoy, my posts. I would permit my blogs to be shared, crediting simply "Alaiyo", but if possible, I have another preference. I feel pretty responsible for the accuracy and usefulness of this "series" in particular, because I don't want to give anyone incorrect or out-of-date information that might be harmful. To be able to control that data, I would prefer if people could be redirected directly to this page, where they will see the most current version. If that isn't possible, then go ahead and re-post, but I would be grateful if the information could be controlled and updated easily by me - should I need to make a change.


Well done on dropping 2 sizes. I disagree, however, with your definition of diet. A diet is what you eat, whether you are trying to lose weight, maintain weight, gain weight or are not trying to have any effect on your weight whatsoever. The problem is that people generally use the word to mean something leading to weight loss.


I agree with you. However, since the context of my post was about weight loss then the implied meaning of the word diet was in reference to that subject.


I love this post. So refreshing to see the facts explained clearly and in one place. Thanks for that.


You are most welcome. I am happy that it is helpful!


Using BMI as an overweight indicator have received bad press here in the UK from time to time, especially with healthy weight initiatives pinpointing children as overweight (because of BMI ranking) when they are obviously not. Thank you for your posts they make for thoughtful reading


I read about BMI having less accuracy for children, and will amend my post to reflect that. You are absolutely correct.


I have always measured body fat (using the special scales) and have been staggered how it has come down since starting running 35% down to 26% I would like to bring it down further....but it seems to be stuck there. I have a good waist but my belly has an annoying fatty layer. I look forward to reading the next blog.


Losing 9% bodyfat is tremendous. Wow! And the next installment is coming very soon.


Thanks for very interesting and informative reading.


Thanks for the above info, with regards to scales mine use details of height, age & gender.

They give figures for weight, % fat, % water which also display in generalised "bands" of low/optimal/moderate/high. I use these only as a personal guide and record weekly on the calendar. BMI does not show though I could calculate this based on info known, but don't.

My main question would be be why does the scale reading for % fat change to go down by 4% when I alter the setting from Normal to Athlete?


Each bioelectrical impedance device uses an algorithm to translate the information it gets from your input and the speed of the electrical pulses, so it can spit out the results. Without knowing the specific mathematical formula, I can't for certain say why it would change. That said, I have a hypothesis: if your scale output has an "athlete" option, and says you magically lost 4% body fat by selecting it, the formula probably assumes a different body composition.

I didn't want to get too far into it in the general post, but here is more on how the device works:

Impure water is highly conductive - like your sweat, blood, etc. Muscles have a lot of impure water in them, as part of their structure.

Adipose tissue (fat) has very little water in it, and because of its chemical structure, it also conducts electricity slowly.

When measuring body fat percentage your are attempting to discern 2 quantities. 1) How much is fat 2) How much is everything else - not just muscle, but also bones, organs, blood, undigested food, everything.

Muscles tend to have a certain percentage of water, bones a different percentage, organs another one again, and so on. And electricity would travel differently through the different tissues. More or less, the amount of water is accurately counted, but how is that divided up into all these different types of lean mass? It is basically a best guess, based upon how most people distribute their body water. So imagine an extreme example: what if all your water was blood, and everything else was nearly dry? You could have practically no muscle at all, tiny thin bones, shrunken organs. But the same amount of fat. You would perhaps be more fatty than normal for a given conductance. Now imagine that we assumed a lot more muscle (and water in the muscle) than normal, with stronger bones and a healthy but proportionately smaller amount of blood? I think conductance would drop for the same amount of water, you would be leaner than the reading would imply.

So my best guess (and it is a guess, not a certainty) is that your scale has different settings to accommodate differing distributions of water in tissues based upon fitness level. In particular, more muscle and strong bones with perhaps less blood volume for athletes.


Think I get it, maybe I have crossed the line between "normal" to "athlete" as all the recent lifestyle changes I have made would no way increase my body fat by 4%. Think I shall go for the athlete setting from now on, if only for the smile within that gives - thank you for sharing your knowledge


I'm not over keen on the bmi readings as they do not take into account us curvy ladies with bra cup size on the bigger side. I am G cup and curvy with bmi of about 27, but my boobs aren't fat but are probably adding quite a bit to my overall weight!


I understand that BMI has its serious limitations. I do want to make sure you have all the information though: breast tissue is not only fat, but it has a lot of fat in it. You may have large pectoral muscles underneath as well, but chances are, with a G cup, there is quite a bit of fat there. And I bet they do weigh a lot, and alter your BMI a fair bit.

In terms of health risks, I don't know that being "curvy" reduces the risk of a high BMI. On the other hand, being muscular and having big bones generally does reduce risks associated with a high BMI. I too am "curvy" and understand the frustration - it may not be plausible for you to aim for a BMI of 19, and that is OK. But as far as I know, having sizable breasts don't directly make BMI readings less valid - although if you also have a small waist, that is a good sign lowering your risk rating.


Thanks, interesting reading. My waist is about 34" so a little above what is considered ok, but not too bad.


Excellent information here...thank you so much for posting this.


Another great post! Keep them coming! You have confirmed some things I knew, and explained other new things to me in such a clear way. You have a gift in communicating complex ideas in a simple way. Thank you for sharing. Looking forward to the next post!


Thank you again !


Weight loss is one of the most sweltering points ever. Everybody is by all accounts attempting to get in shape these days. However what's the contrast between weight loss & fat loss? Individuals appear to utilize both terms reciprocally. In the wake of perusing this post you'll comprehend the contrast between weight loss & fat loss, additionally which one you ought to go for and how. Weight Loss vs. Fat Loss.

What's the distinction?

How about we begin by characterizing weight loss & fat loss so you realize what I mean here. Weight Loss. You need to bring down your body-weight, the total weight of your bones, muscles, organs, muscle to fat ratio ratios, … Fat Loss. You need to bring down your muscle to fat quotients, the measure of fat your body conveys. Solid objectives are 10% muscle to fat ratio ratios for men and 15% for ladies. Issues with Weight Loss. On the off chance that you need to get in shape, its in all likelihood in light of the fact that you convey an excess of fat. There are individuals who must get more fit, in the same way as competitors before a rival, however most need fat loss. So quit weighing yourself.

Inconsistent. Your body-weight can change day by day since its affected by your stomach/entrail/bladder substance, water loss/maintenance, muscle loss/addition, fat loss/pick up, … You'll have no clue what's going on. Unessential. 2 individuals with comparable stature can weigh the same, yet look totally changed on the grounds that one has lower muscle to fat quotients than the other. Check the picture at the top for a sample. The last point shows why the BMI standard is imperfect: it doesn't consider your muscle to fat quotients.


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