When should you start calorie restriction?

[qwntia]

This says:

children, adolescents, and young adults (under approx 21) should be advised against starting CR. Physical growth may be impaired by calorie restriction, as observed in lab animals. In addition, mental development and physical changes to the brain take place in late adolescence and early adulthood that could be negatively affected by calorie restriction. For this group, the best advice is to follow a normal (non-CR) diet until reaching early twenties.

However, according to this, brain development continues "well into our 20s" (i.e. beyond approx 21). I am wondering if starting CR in one's early or mid 20s would impair brain development. I recall reading that CR can also slow brain deterioration, though, so it might be the case that starting CR in one's early or mid 20s would still be a net positive for brain functioning in the long term.

 

Any relevant insights would be appreciated.

[Gordo]

First you have to define CR before anyone can comment on how beneficial it may be or what age to start. 

[qwntia]

First you have to define CR before anyone can comment on how beneficial it may be or what age to start. 

By CR I mean calorie restriction, of course. What else did you want specified?

[Gordo]

 

First you have to define CR before anyone can comment on how beneficial it may be or what age to start. 

By CR I mean calorie restriction, of course. What else did you want specified?

 

For instance, I consider myself "doing CR" because I eat fewer calories than I did when I was true "ad lib" feeding, and fewer calories than an average American of my height and gender.  Others here seem to have different criteria.  At any rate, serious calorie restriction will impact both physical and mental growth and development.  Some would argue that this is the goal, so what's the problem?  On the other hand if your idea of CR just means eating lots of fruits and veges and not allowing yourself to be overweight, then you are golden.

Edited May 10, 2018 by Gordo

[mccoy]

CR is actually not very easy to define. I prefer Michael Rae's definition since it provides an objective benchmark, that is, one's weight in one's late twenties, to be decreased by at least 15%.

 

I cannot answer the question but I would wait, as a precautionary measure, for my thirties, in the meanwhile being happy to practice a CR mimicking regime like gordo describes, based on healthy, hormetic plant-based food.

 

As a very personal and debatable opinion, I believe that CR as above defined is very good for overweight persons, with a metabolism which favours fat accumulation, whereas its benefits may be dubious for naturally lean people.

[Matt]

I started decreasing my weight when I was 18 years old, but at certain points in my life, I was quite skinny from all the exercise and not eating much. And giving my dog the food under the table (especially meat, which I hated).

 

I don't think my brain is underdeveloped. Although, I am prone to a few typos here and there, so who knows? :p

 

Seriously though, I have pretty good self-control, and I'm not exactly dumb, and generally emotionally stable and rational. My brain seems to have developed fine. I'm not exactly a genius either though! My strengths are more in communication and language than math.

I think the environment and home you grow up in is going to have a much bigger impact on your brain development than eating fewer calories. 

 

My BMI from age 20 to 26? was around BMI 16.3

 

I wouldn't personally drop that low again though. In fact, I can eat fewer calories now than when I was 20 and I maintain a higher weight. Feels like my metabolism has slowed a lot.

Edited May 10, 2018 by Matt

[qwntia]

 

 

First you have to define CR before anyone can comment on how beneficial it may be or what age to start. 

By CR I mean calorie restriction, of course. What else did you want specified?

 

For instance, I consider myself "doing CR" because I eat fewer calories than I did when I was true "ad lib" feeding, and fewer calories than an average American of my height and gender.  Others here seem to have different criteria.  At any rate, serious calorie restriction will impact both physical and mental growth and development.  Some would argue that this is the goal, so what's the problem?  On the other hand if your idea of CR just means eating lots of fruits and veges and not allowing yourself to be overweight, then you are golden.

 

Thank you for the explanation. Do you know of any resources to help estimate the minimum amount of calories needed to avoid inhibiting brain development for someone whose brain is not yet fully developed? I know one is considered underweight if one's BMI is less than 18.5, so I was wondering if restricting caloric intake would be okay if BMI is kept above that.

[qwntia]

I started decreasing my weight when I was 18 years old, but at certain points in my life, I was quite skinny from all the exercise and not eating much. And giving my dog the food under the table (especially meat, which I hated).

 

I don't think my brain is underdeveloped. Although, I am prone to a few typos here and there, so who knows? :p

 

Seriously though, I have pretty good self-control, and I'm not exactly dumb, and generally emotionally stable and rational. My brain seems to have developed fine. I'm not exactly a genius either though! My strengths are more in communication and language than math.

 

I think the environment and home you grow up in is going to have a much bigger impact on your brain development than eating fewer calories. 

 

My BMI from age 20 to 26? was around BMI 16.3

 

I wouldn't personally drop that low again though. In fact, I can eat fewer calories now than when I was 20 and I maintain a higher weight. Feels like my metabolism has slowed a lot.

Thanks for the input. That said, since your experience is a case study and since it's hard to determine what your intelligence would have been if you kept a higher BMI (because there's no control group), the evidence your experience provides is extremely weak. It does provide significant evidence that starting CR when ~18 doesn't have a massive effect on intelligence, but I wouldn't have thought there was one, a priori, considering brain already undergo a lot of development before the age of 18 (18-year-olds aren't that dumb, after all).

[Matt]

I was thinking more about your question earlier. The prefrontal lobe continues to develop throughout our 20s, and expect if anything, CR may impact this development. Although I am not a neurobiologist and haven't really studied this area either.

 

But things like risk-taking, impulsivity, addiction and those sorts of things could be greater if this part of the brain were underdeveloped due to caloric restriction. I can only provide my anecdotal story, but I am none of those. I'm far from impulsive, I've never had any addiction problems, and I'm not exactly a big risk-taker (especially if compared to male population).

 

When I look back, I don't think I was dumb at 18, but most of my education came after I left high school. 

 

But yeah, *weak* evidence.

 

All that being said, if you're a Lemur, apparently CR does have an effect on the brain  

 

This kind of thing hasn't really been studied in people who've done CRON from a young age. There is probably some data from girls with eating disorders and brain development and impoverished populations, but that's not exactly the kind of information we can use either.

I don't know what reasoning is being *21* for starting CR. Perhaps CRSociety is just being cautious, or maybe there is good reasoning for it. Also, how many extra good years (assuming CR translates well to humans) could you get from waiting until your late 20s anyway?
 

I think it would be harder to tweak metabolism and optimize the system in your 20s (to slow aging) than it would be if you are over 30. 

 

Well, I'm very happy I started when I did. No regrets. But I'm just one little case. :)

Edited May 11, 2018 by Matt

[qwntia]

I was thinking more about your question earlier. The prefrontal lobe continues to develop throughout our 20s, and expect if anything, CR may impact this development. Although I am not a neurobiologist and haven't really studied this area either.

According to this, eating disorders can indeed cause brain damage. Of course, this doesn't mean CR does due to CR practitioners having good nutrition and perhaps less extreme restriction of calories. (I take it when you say prefrontal lobe you mean prefrontal cortex.)

 

I think it would be harder to tweak metabolism and optimize the system in your 20s (to slow aging) than it would be if you are over 30.

Interesting. What is your evidence for this?

[qwntia]

Wikipedia says, "An underweight person is a person whose body weight is considered too low to be healthy." Impaired mental development sounds unhealthy to me, so this suggests CR wouldn't inhibit mental development as long as you avoid being underweight. Does this sound reasonable to you all?

[mccoy]

1 hour ago, qwntia said:

Wikipedia says, "An underweight person is a person whose body weight is considered too low to be healthy." Impaired mental development sounds unhealthy to me, so this suggests CR wouldn't inhibit mental development as long as you avoid being underweight. Does this sound reasonable to you all?

Yes, but some in this forum would debate that without being underweight (compared to the average reference) you're not practicing real CR.

So, a mild CR a-la-Gordo with nutrients optimization and mostly plant-based foods sounds like a safe route, apt to the non-gamblers.

The concept of CR in fact sounds like gambling:  severe CR is hypothized to result in greater longevity, but that's not really proven in humans and severe CR might also result in severe health problems. A very thin razor-edge.

 

 

[Todd Allen]

Basing CR off of calories is problematic because it is difficult to establish an appropriate goal and it is difficult to accurately track calorie consumption, burn and losses through excretion, etc.  Scale weight also has issues.  One could be gaining fat while losing muscle, bone or water while the scale suggests all is good.

I think it best to have a body composition goal and then track body composition and adjust diet, exercise and perhaps the goal as needed for satisfaction.  There are many tools to track body composition, the worst probably being an impedance based smart scale.  A tape measure and an interpretative calculator can get one pretty far, search "tape measure body fat calculator" to find many options.  Skin fold calipers can be an improvement though they take more care to produce consistent results.  A dexa scan is a good way to establish a baseline for better calibrating more frequent testing of home measurements.

[Clinton]

Todd,

imho you raise the most important (non-lab) physical metric to monitor: body composition.

Wrt all-cause mortality BMI correlation is not ideal for a few reasons but what does seem clear is that the lowest level of body fat is most protective.

Clinton

 

[mccoy]

1 hour ago, Clinton said:

... but what does seem clear is that the lowest level of body fat is most protective.

We should maybe add the lowest level of visceral fat, since bodyfat as a whole may have an optimum which varies according to age and physical exercise.

For example, a 4-5% level is only achievable by competitive bodybuilders after strenuos effort and compulsive dehydration, with the aid of diuretic drugs.

Such a low value in the general population would usually suggest a state of starvation.

Also, if we read some previous discussions of this forum, a certain amount of bodyfat in elderly people seems to be protective.

[Saul]

3 hours ago, Clinton said:

what does seem clear is that the lowest level of body fat is most protective.

I agree.  (Mine was tested by DEXA by Luigi Fontana, and also during CRONA.)

Perhaps a way to get an approximation to visceral fat is to compute the waist to hip ratio (far from perfect, but much better than BMI).

  --  Saul

[corybroo]

I’d say this study answers the question “When should you start calorie restriction?” with TODAY, at least for adults.  It found that benefits of a lower calorie, healthier diet start even after the majority of an age cohort has died.

Study shows obese flies live longer on a diet at any age

Old, obese flies get healthier and live longer if put on a diet, University of Connecticut researchers report on Dec. 8 in PNAS. 

Fruit flies live short and fast—the lifespan of flies raised on a high-calorie diet is less than 80 days, while the longest-lived on a low-calorie diet can reach 120 days. 

In this study, they looked specifically at male flies. Young flies switched from a high-calorie to a low-calorie diet at 20 days old lived very long lives, similar to the flies fed a low-calorie diet from day one.

What surprised the researchers was that switching the flies' diet to a low-calorie one remained a reliable way to extend lifespan even for old flies in ill health.

[The older insects] had a higher death rate than flies raised on the low-calorie diet. But when the surviving high-calorie flies were switched to a low-calorie diet at 50 or even 60 days (when most of the high-calorie flies had already died) their metabolisms changed, their death rate plummeted, and their lifespans lengthened.   [Emphasis added CB]

"The remarkable finding of this study is that even after living a significant portion of their lives on a high-calorie diet, flies can gain the benefits of life span extension by simply switching to a low-calorie diet," Graveley says.

Since many basic metabolic pathways in fruit flies are shared with humans, this study suggests that human metabolism may respond the same way, and individuals eating a high-calorie diet could benefit from reducing their calorie intake in old age.