The Weekly Thread: the science of why your metabolism slows with age, “carry” for life, and empathy provides clarity.


Why does our metabolism slow as we age?

A paper I recently came across titled, “Metabolic changes in aging humans: current evidence and therapeutic strategies” aimed to best answer that question based on a review of data showing changes in fat gain (adiposity), muscle, and hormones related to aging. 

Here’s what they found. 

As fat cells get older, they begin to misbehave, and this dysfunction does cause them to hold on to fat more tightly. 

Furthermore, a newer discovery was made. The authors state in the paper:

Immune cell infiltration increases with age, and accumulation of age-dependent regulatory cells is seen. This is a newly characterized aspect of fat cell biology.” 

This new discovery shows that as you age, this accumulation of immune cells in your fat cells causes the fat cells to misbehave, and this is a new factor for consideration (and further research) as to why your fat cells become more stubborn with age. 

As you age, you also have an accumulation of senescent fat cells, if they don’t go through apoptosis and die, they recruit other functional fat cells to then also act like senescent cells, causing further fat cell dysfunction. 

What are senescent cells? 

Senescent cells are cells that have entered a state of irreversible growth arrest, meaning they no longer divide and proliferate. They are characterized by changes in gene expression and the secretion of various molecules, collectively known as the senescence-associated secretory phenotype (SASP). 

Senescent cells can accumulate in tissues over time and are associated with aging and age-related diseases. While senescence serves as a protective mechanism to prevent damaged cells from becoming cancerous, the accumulation of senescent cells can have detrimental effects on tissue function and contribute to age-related decline. 

Senescent cells are often referred to as “zombie cells”, and are oftentimes at the heart of our autoimmunity, cancer, and now we’re realizing, fat or weight gain. 

How do we stop “zombie (senescent) cells” from accumulating?

Through a process known as apoptosis. 

Apoptosis, also known as programmed cell death, is a natural process that eliminates unwanted or damaged cells in a controlled manner. It plays a crucial role in maintaining tissue homeostasis and removing cells that are no longer needed or that pose a risk to the organism. 

In relation to senescent cells, apoptosis serves as a mechanism to eliminate these cells from tissues. Ideally, senescent cells should undergo apoptosis and be cleared from the body. However, in some cases, senescent cells evade apoptosis and persist in tissues, leading to their accumulation. This impaired clearance of senescent cells can contribute to the detrimental effects associated with aging and age-related diseases.

What induces apoptosis?

Certain longevity-boosting lifestyle habits such as exercise and fasting induce apoptosis. There are also certain research backed herbs known as “Senolytics” that will induce apoptosis just through consumption.

I know recommending exercise and fasting (both intermittent and periodic extended fasting) probably isn’t super noteworthy, however, what this research shows us is that there’s far more benefit to exercise and fasting from a fat loss perspective. This also shows us that there’s a far greater picture to paint with respect to fat loss being more than just calories in and calories out. 

Gaining a greater understanding of all the mechanisms at play that benefit us from positive lifestyle habits like fasting and exercise, will help you better understand what’s going on inside the body, and maybe leave you placing an even greater emphasis on implementing said lifestyle habits into your life.

Okay, back to the research findings. 

Hormones & Metabolism

Serum DHEA levels in both men and women are found to be lower with age, and this typically precedes menopause in women, and the general lowering of testosterone in men as they age. 

The connection to lower serum DHEA and then lower estrogen/progesterone in women, and testosterone in men, is linked to an increase in post-meal fat storage, and a decrease in lipolysis of the fat tissue. 

In short, your fat cells are not functioning properly due to the decrease in these hormones, and that causes them to retain more fat, and have a lower propensity to burn fat. 

Furthermore, this propensity to accumulate more fat as a result of hormone imbalances, causes greater fat infiltration in organs like your liver, which can then cause health issues, and your pancreas, which can cause insulin resistance, and that can cause a host of issues from weight gain, to diabetes, and inflammatory-related diseases. 

To sum it up, senescent cell accumulation increases everywhere in the body as we age, (this includes fat cells) simultaneously, key hormones decrease, causing hormone imbalances, and these two key factors cause fat cell dysfunction and misbehavior, and this dysfunction causes fat cells to become more stubborn, thus increasing their propensity for fat storage, and decreasing their propensity for fat burning (lipolysis). 

Okay, so we’ve learned from this research that if we can cut down on the accumulation of senescent cells through exercise, fasting, and supplementing with Senolytics (which also reduces risk of all other age-related diseases), and gaining a more optimal hormone balance, we can negate some of the negative effects aging has on our body’s ability to burn fat. And if we can negate some of these factors, we can then more easily get back to “calories in vs. calories out” as the main factor affecting our ability to burn fat. 

Next week, I will share some research showing how hormone level fluctuations are quite seasonal, and how understanding what is causing this (it all goes back to getting natural light) can help you naturally hack your biology to better optimize your hormones. Before we close out this segment, I’ll share one quick hack for optimizing age-related hormone decline.

Boosting DHEA

As mentioned above, there is a direct link between a reduction of serum DHEA levels preceding a decrease in estrogen/progesterone in women, and testosterone in men. 

So, if there is substance to this correlation, this would mean that if serum DHEA levels were increased, estrogen/progesterone would increase in women, and testosterone would increase in men. 

This does in fact, appear to be the case for most men and women. 

To understand why, we must first understand what DHEA is. 

What is DHEA

DHEA, which stands for dehydroepiandrosterone, is a hormone produced by the adrenal glands. It is a precursor hormone, meaning it can be converted into other hormones such as estrogen and testosterone in the body.

DHEA plays a role in various physiological processes and is involved in the regulation of the endocrine system. It has been recognized for its potential influence on mood, energy levels, and overall well-being. DHEA levels tend to peak during young adulthood and gradually decline with age.

Supplementing with DHEA

DHEA has oral bioavailability, and is inexpensive, so it’s a pretty easy addition if trying to optimize hormones to reduce the effects of aging on the body. 

DHEA supplementation for women seems to be most effective starting at perimenopause and beyond, and for men, around the age of 40, when testosterone levels start to decline fairly significantly with age. 

Women typically benefit from 2.5mg of DHEA per decade of life, and men from 10mg per decade of life. 

So, a 50 year old perimenopausal woman would supplement with 10-15mg of DHEA, and a 50 year old man might supplement with 50mg of DHEA. 

Movement for Life #6: Carry

This week’s “Movement for Life” is a “carry”.

Everything I outline in this segment (with video tutorial links) are movements that require no more than a single kettlebell, and can be done anywhere, and don’t need to be part of an actual exercise regimen. 

If not part of an exercise regimen, just work these movements into your life and day throughout the week, as when put together over time, will build functional strength, increase mobility, and boost your metabolism. All things that will benefit you tremendously as you age. 

These movements are ideal for kids and young teens to work on specific mobility and reduce risk of injury in sports, all the way up to the eldest of adults, and everyone in between.

A Quick Primer on the “Carry”

“Carrying” movements with a kettlebell refer to exercises that involve holding and walking or moving with the kettlebell. These movements focus on building core stability, grip strength, and overall body strength. 

Here are a couple of examples of carrying movements you can do with a single kettlebell:

1. Suitcase Carry. Hold a kettlebell in one hand, allowing it to hang by your side, and walk while keeping an upright posture. This exercise challenges your core and lateral stability, as you need to counterbalance the weight on one side. CLICK HERE to watch a quick tutorial. 

2. Overhead Carry. Press a kettlebell overhead and stabilize it while walking. This exercise strengthens your shoulder stability, core muscles, and upper body. CLICK HERE to watch a quick tutorial. 

Empathy Provides Clarity 

The human condition is an incredible fascination of mine. 

On one hand, we’re all humans, all facing many of the same concerns, wants, and needs in life. 

On the other hand, when you peel back from those core concerns, wants, and needs of all humans, there is a tremendous amount of nuance. 

Different socioeconomic backgrounds, different problems in one’s daily lives, different education, upbringing, and so much more. 

This all shapes how we individually respond quite variably to many of the same issues and problems we all face. 

As I try to understand more and more about this amazing, eclectic mix of life we call the human condition, I’m making a conscious, concerted effort to look more closely at other’s perspectives, especially if I disagree with them on something, or we collectively, have a disagreement. 

Oftentimes, I will still walk away disagreeing with said individual, however, through trying to first better understand their worldview, I gain greater clarity on their perspective, on where they’re coming from, and why. 

By making more of an effort to make first acting with empathy my baseline, I find I gain greater clarity on my own thoughts, and on the world as well. 

Is this person who is upset or lashing out at me really just stressed out in their own life about certain things, and not dealing with it in a meaningful way? 

Is this causing them to react the way they are to me? 


And it’s still not an excuse to lash out at someone or take something out on someone, however, through first acting with empathy, you expose the “why” that might be causing them to do this. 

Through this clarity, you are more likely to deal with said individual in a better, more constructive manner, which is better for both of you.