Relative intensity of diet

[Dominique]

We are often asking ourselves what caloric deficit we should use to lose weight in a sustainable manner, but usually think in absolute terms: for instance, should it be 500 or 1000 calories? One way to make it more relative is to aim at losing a certain amount of weight as a percentage of bodyweight: for instance, 1% of bodyweight per week, 10% of starting weight  over three months. However, this still doesn’t fully take into account what I would call the "relative intensity" of the diet. I’ll try to explain what I mean using two hypothetical subjects, A and B.

A is a 60-year-old woman, 5’ 2 tall, 164 lbs, sedentary.

B is a 30-year old man, 6’ tall, 221 lbs, highly active.

Both have a BMI of 30.0, so are presumably carrying quite a bit of extra weight for their own good.

Person A has a BMR of 1267 calories and a TDEE of 1521 calories.

Person B has a BMR of 2000 calories and a TDEE of 3451 calories.

For the sake of simplicity, I’m using the standard equation found in this online calculator, which obviously doesn’t take into account any individual differences (possible medical conditions etc.).

Let’s assume both go for the standard 500 calories daily deficit, which is supposed to result in a weight loss of 1 pound per week. Person A would be eating 1021 calories, which is  246 calories below her BMR and 67% of what her body would normally need at maintenance. Person B would be eating 2951 calories, which is 951 above his BMR and 86% of his maintenance level. Clearly, that same absolute deficit would be much harder to sustain for A than for B. Person B could very well go for a 1000  calories deficit and still be better off: he would still be eating 451 calories above his BMR and 71% of his maintenance calories.

Of course, B would need to lose 37 pounds to bring his BMI down to 25.0, while A would "only" need to lose 27.5 pounds.

In that example, we saw there are several variables that affect the relative intensity of a diet: gender, age, size (height / weight) and activity. Of these, weight and activity are the only ones we can have an impact on, and weight is what we are trying to change, so this leaves us with activity as the only true adjusting variable.

I’ve tried to put this into practice in my own dieting efforts: since I can’t change the fact I’m 57-yo and 174 cm tall (which results in a relatively low BMR), I’ve strived to significantly up my activity level from my usual baseline while actively dieting down to a lower weight. During my last weightloss phase, I estimated I ate 1178 calories above my BMR, for a relative intensity of 83% of my maintenance level. I was able to lose about 6 kg in 12 weeks (starting from a relatively lean level), without feeling extremely hungry at any time, nor completely depleted towards the end.

So while weightloss success is primarily about eating, activity can be a significant contributor too.

[Baltoscott]

@Dominique -- your hypothetical example nicely illustrates one of the reasons why, when a lot of couples  "go on a diet together," the larger person (usually the man in male/female couples) seems to lose weight more more "easily."  The daily burn is just higher for bigger people even if the BMI is the same.  

Adding movement helps a lot in getting to the point of be able to lose weight without going to extremely low levels of calorie consumption.

[lavabelle]

@Dominique your example definitely confirms what I have personally experienced. I increased my activity by quite a bit, and even though I am more hungry, I actually get to eat!!! I eat quite a bit and this helps me not feel deprived and keeps me fueled to stay active. I could not imagine trying to lose weight by diet alone...I don't think I could be successful at it. I would have to eat such small amounts of food to shed the weight and I would be very cranky and miserable or Hangry :). And eating so few calories would make it very difficult to carry on the duties of my very busy life, full time job as a teacher, and a business I have to run on evenings and weekends. I need to EAT!! to remain sane and healthy! 😉

Thanks for this great example 🙂

[SunsetRunner]

@Dominique the interesting thing about exercising is that it plays lot more important role during weight loss and maintenance than just burning a few extra calories. Trying to answer a question of why I am always hungry I found out that probably I'm leptin resistant ( sometimes called "brain starvation" ) which is something I had to build when I was obese. It's really hard to retrain the brain even after such a long time. Even if my body is about to explode, my brain still tells me to eat. It's very frustrating. Adding more exercise, however, helps me with managing this situation. One, it makes me burn more calories daily but also, what is a lot more important to me, it suppresses hunger. Exercising makes me consume less food because my brain is not craving for it. It helps during weight loss and is still a big help when you try to keep the weight off. That's why I have my small theory that active people stay fit not because they are active but because they consume less food. It's easy to eat more than one burned during exercising but if the brain is not demanding to be fed it's much easier to control the situation.

[MVibe]

Good post. This is something I am addressing at the moment.

I'm 46, 5'9 and weigh 155lbs with 19% bodyfat - which is a healthy weight for my frame. When i got my Fitbit Blaze I weighed 186 lbs with 27% bodyfat. I never really thought about BMR TDEE and wasn't too clued up on it when I got the Blaze, I simply made a plan and went on a 500 cal deficit and did 1000 steps a day. That and diet change saw the excess weight literally fall off in hardly any time at all. I'd hardly put in any effort that it felt like cheating or something.

Anyway, what seems to me to be a lot more tough, is when you're at a healthy weight but you now want to get an athletic physique. And why not? If you get so far, it makes sense that you'd want to continue to make new goals to keep you motivated. The issue is though with me at least, is any sort of deficit in my calories now could potentially see me eating below my BMR - which is about 1600 cals a day. If I entered a -250 cals a day deficit on fitbit plan, without activity, it would have me eat about 1350. I'm eating on average 1700 to 1900 a day and sometimes wonder if that is a little too low but I feel fine, weight is stable and bodyfat is very, very gradually coming down. It's at this point that I'm aware that any further physical changes I wish to make are going to have to be 'earned' by increasing physical output, increasing things like resistance training, cardio. The issue I have however is whether I maintain my current level of eating or increase it but what I don't want to do is increase my food intake whilst increasing my activity and be exactly on a balance - which is pretty much where I am now. The other issue is, without increasing food intake, I'm not giving myself enough enery for the actual added demand.

It's a head scratching thing for me at the moment so if anyoe can chime in with some suggestions, I'm all ears. 🙂

[bikerhiker]

The comparison between a 60 year old woman and a 30 year old man is not really fair.  First of all, women tend to store "MORE" body fat compared to a man, so using BMI is completely moot.  The American Journal of Nutrition published a study that illustrates below..

Body Fat Guidelines

Age Healthy Body Fat % (Women) Healthy Body Fat % (Men)

20-39 21%-32% 8%-19%

40-59 23%-33% 11%-21%

60-79 24%-35% 13%-24%

As you have noticed, a 60 year old healthy woman's body fat % is between 24-35%, whereas the 30 year old man's healthy body fat% is between 8-19%.  So obviously, the heavier the weight the person is, the more body fat you will burn and the more weight you will lose.  But to suggest that a 60 year old woman should MATCH the body fat loss rate of a 30 year old man which weight more is not only irresponsible, but rather misguided in nature.  Because no matter how much exercise intensity and extreme diet regime the 60 year old woman @ 24-35% healthy body fat tries to achieve comparable to a 30 year old man at 8-19% healthy body fat, the 60 year old woman will not only have to work extremely hard and do extreme dieting to achieve a body fat of 8% to 19%, it poses an extreme health threat to a 60 year old woman as well.  You can end up in the emergency by doing that!  The problem with these type of comparisons is that, it is focused only on body weight, not on age and body fat.  But truly, BODY FAT is the culprit, not body weight.  You can have a relatively thin body, but has a high amount of BODY FAT.  Body fat is the culprit for high blood pressure, type 2 diabetes and heart related disease like stroke.

The problem with this hypothesis is that, it is very difficult to measure your body fat with a Fitbit Aria scale or any scale that uses bioimpedance.  It is not so accurate unfortunately.  The most accurate method are

1, Underwater weighing

2, Body pod

3, DEXA (Dual X-ray Absorptiometry) 

Water is a fantastic way to determine whether you have too much lean mass or body fat.  It's simple really.  If you are a swimmer and you float relatively easily on water, then you have a higher body fat content than a swimmer who have to do a lot of more work threading water because he/she has more lean mass.  Lean mass sinks, body fat floats.

Another thing that's inaccurate is that, you burn calories while you exercise, but most of those calories are not necessarily fat.  When you exercise, or increase your intensity in exercising, you are telling the body to adapt to a higher intensity exercise routine, which means that you are building muscles and depleting completely your muscle glycogen storage.  If your intensity is super high enough which depletes your Type 2X muscles, it multiples the muscles' ability to burn fat at rest.  This multiplication process is called Mitochondial Biogenesis.  During your recovery phase, you will be burning your fat storage during rest and sleep.  But no matter how much high intensity the 60 year old woman tried to do, she will never reach and meet the abilities of the 30 year old man or even a 60 year old man, as a woman needs a bit more body fat to keep herself healthy.  

Having body fat is a kin to having a rainy day fund.  During boom times, a rising tide raises all ships, but during a recession is when you see who has a rainy day fund or not.  During a recession, those who have savings can weather the storm and allow themselves to find a new job or gig even during long periods of unemployment.  For those who don't have a rainy day fund however, will succumb to loss of employment and be on the poverty line which can lead to death.  It's the same with body fat.  The purpose of body fat is to allow you to have a backup for your body to lean on during times of serious illness.  You may get it or you may not, but truly if it's there for you to rely upon during times of sickness, then you can live for another day.  Unless you have a crystal ball that guarantees you will never ever get a serious illness, that's fine.  Be thin and be at a lower fat %, but truly to suggest that people must achieve this low body fat% without disclosing the reason for having a health body fat is, to me, rather an unfair comparison. 

[Dominique]

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@MVibe wrote:

Anyway, what seems to me to be a lot more tough, is when you're at a healthy weight but you now want to get an athletic physique. And why not? If you get so far, it makes sense that you'd want to continue to make new goals to keep you motivated.

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Sure, that’s exactly how I see things: it’s not a finite process with a beginning and an end, it’s open-ended/never-ending!

It's at this point that I'm aware that any further physical changes I wish to make are going to have to be 'earned' by increasing physical output, increasing things like resistance training, cardio. The issue I have however is whether I maintain my current level of eating or increase it but what I don't want to do is increase my food intake whilst increasing my activity and be exactly on a balance - which is pretty much where I am now.

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Changing body composition involves losing fat and gaining muscle. While it may be possible to do both if/when you are significantly overweight, it’s very hard once you are at a normal/healthy weight, which appears to be the case for you. The optimal way to do it (so I’ve been led to believe) is to do things sequentially, alternating between fat loss phases (when you are eating at a deficit) and muscle gaining phases (when you are in a caloric surplus), possibly interspersed with maintenance phases (to let your body get accustomed to the new lower fat level, or the newly gained lean mass).

Cardio training is particularly useful when losing fat, as it will allow you to eat enough food while still being in a deficit. It obviously also has benefits from a general health and fitness perspective. Resistance training is what it takes to gain muscle (while in a caloric surplus), and to preserve lean mass (while in a caloric deficit). Diet-wise: eat enough protein (to built muscle/preserve lean mass), enough carbs (to fuel your resistance training workouts), get the rest of your calories from healthy fats (needed for hormonal balance); generally speaking: get most of your food from whole/minimally-processed sources,  eat your veggies & fruits (micronutrients and fiber).

I’ve been experimenting with this for the past couple of years. The latest fat loss phase (early June to early September, 12 weeks) went well, with BF% going from 17.5 to about 13.5%:

I had planned to have an 8 weeks maintenance phase after it (currently on week 6/8), but I’m pondering whether I should make it longer. This is because BF% has continued to decrease, albeit very slowly, even though I’m no longer in a deficit.

The challenge for me is gaining weight slowly enough, so as to minimize fat gains. My next attempt will be to gain at no more than 0.2-0.3 kg per week in average, and hopefully end up with a BF% lower than 17+, where I was last June.