Relationship between bodyfat, diet and SHBG

I have read that higher bodyfat raises leptin and that higher leptin can lower SHBG. Does this mean that losing bodyfat can raise SHBG? I have cut down from 85 to 78kg but also found that I needed to up my daily dose slightly.

I have noticed another observation that is really strange. After I have eat 150g of chicken breast I feel somewhat flat and more anxious in what feels like low testosterone way. I have been having issues with a perceived lack of potency of my testosterone the last couple of months and I am wondering if it's to do with some sort of shift in SHBG. When I was higher bodyfat I almost felt like my mind and body felt better and more stable. I am wondering whether I have just got too lean (sub 10%), or the fat loss has somehow affected SHBG?

 

Losing body fat has a significant impact on sex hormone-binding globulin (SHBG) levels, as evidenced by multiple studies. Here is a detailed summary of the findings:

Impact of Weight Loss on SHBG​

General Findings​

1. Increased SHBG Levels: Weight loss, particularly the reduction of body fat, is associated with increased levels of SHBG. This increase in SHBG is beneficial as it reduces the levels of free, biologically active sex hormones like estradiol and testosterone, which are linked to various health risks, including breast cancer in postmenopausal women.
2. Degree of Weight Loss Matters: The extent of weight loss correlates with the increase in SHBG levels. For instance, a study found that participants who maintained any degree of baseline weight loss at 30 months had significantly greater increases in SHBG compared to those who did not lose weight or gained weight. The increase in SHBG was proportional to the degree of weight loss, with the highest increase observed in those who lost ≥10% of their body weight.

Specific Studies​

1. Postmenopausal Women: In a study involving overweight/obese postmenopausal women, those who underwent a diet and exercise intervention showed significant increases in SHBG levels compared to controls. The study concluded that sustained weight loss results in reductions in free estradiol and testosterone and increases in SHBG 18 months post-intervention.
2. Massively Obese Men: Research on massively obese men who underwent biliopancreatic diversion surgery showed that weight loss led to a significant increase in SHBG levels. The study highlighted that achieving near-normal body weight could normalize SHBG concentrations, which is beneficial for reducing the risk of diabetes and cardiovascular diseases.
3. Exercise vs. Diet: Another study compared the effects of weight loss induced by exercise versus a hypocaloric diet. It found that exercise-induced weight loss led to a more favorable body composition and larger increases in SHBG compared to diet-induced weight loss. This suggests that the type of weight loss intervention can influence the degree of change in SHBG levels.
4. Rapid Weight Loss: In abdominally obese men, rapid weight loss through a very low-calorie diet resulted in a significant increase in SHBG levels. Although SHBG levels decreased slightly during the weight maintenance phase, they remained higher than baseline levels, indicating a sustained benefit.

Mechanisms​

1. Body Fat and SHBG Production: The reduction in body fat, particularly abdominal fat, is crucial in influencing SHBG levels. Fat tissue is a significant source of estrogen production post-menopause, and its reduction leads to lower estrogen levels and higher SHBG levels.
2. Dietary Influence: Diet composition also plays a role in SHBG levels. For example, a low-fat diet has been shown to increase SHBG levels, while a high-fat diet decreases them. This suggests that dietary modifications, along with weight loss, can further influence SHBG concentrations.

Health Implications​

1. Breast Cancer Risk: Increased SHBG levels due to weight loss are associated with a reduced risk of estrogen-sensitive breast cancers in postmenopausal women. This is because higher SHBG levels result in lower levels of free estradiol, which is linked to breast cancer risk.
2. Cardiovascular and Metabolic Health: Higher SHBG levels are beneficial for cardiovascular and metabolic health. They are associated with lower risks of conditions like diabetes and cardiovascular diseases, which are prevalent in obese individuals.

In summary, losing body fat significantly increases SHBG levels, which has various health benefits, including reduced risks of breast cancer, diabetes, and cardiovascular diseases. The degree of weight loss and the method (diet vs. exercise) can influence the extent of these changes.

Sources:

1. Long-term Weight Loss Maintenance, Sex Steroid Hormones and ...

2. Achievement of near-normal body weight as the prerequisite to ...

3. Effect of weight loss, with or without exercise, on body composition ...

4. Diet and Sex Hormone-Binding Globulin - Oxford Academic

5. Study finds that moderate weight loss reduces levels of sex ...

 

...
Increased SHBG Levels: ... This increase in SHBG is beneficial as it reduces the levels of free, biologically active sex hormones like estradiol and testosterone, which are linked to various health risks, including breast cancer in postmenopausal women.
...

This is probably not a causal relationship. There is not a plausible reason for an isolated change in the binding protein level to influence free hormone levels after a new steady state is achieved. Reiterating a thought experiment: If you take away half of a person's SHBG along with what's bound to it, what causes a change in free hormone levels? The answer is nothing, because the body measures free hormone levels to regulate these hormones, and they haven't changed.

...
Postmenopausal Women: In a study involving overweight/obese postmenopausal women, those who underwent a diet and exercise intervention showed significant increases in SHBG levels compared to controls. The study concluded that sustained weight loss results in reductions in free estradiol and testosterone and increases in SHBG 18 months post-intervention.
...

This correlation does not imply causality. Calorie restriction alone suppresses hormone production in the HPT axis. In addition, in women, "insulin resistance or high insulin can stimulate ovarian cells to make more testosterone. That happens with PCOS and menopause."[R] Losing weight can reduce insulin and therefore testosterone and estradiol as well.

...
Body Fat and SHBG Production: The reduction in body fat, particularly abdominal fat, is crucial in influencing SHBG levels. Fat tissue is a significant source of estrogen production post-menopause, and its reduction leads to lower estrogen levels and higher SHBG levels.
...

This statement is puzzling given that estrogens tend to increase SHBG. In accordance with the previous quote, it may actually be a reduction in testosterone that's driving this. We've seen that testosterone has a stronger influence on SHBG than the estrogen formed from it via aromatization. Alternatively, referencing the OP, there is a negative association between leptin and SHBG. However, so far I haven't come across research establishing causality.

...
Dietary Influence: Diet composition also plays a role in SHBG levels. For example, a low-fat diet has been shown to increase SHBG levels, while a high-fat diet decreases them. This suggests that dietary modifications, along with weight loss, can further influence SHBG concentrations.

This review article downplays the influence of diet on SHBG and attributes the bulk of the effect to weight loss.

Reduced caloric intake leading to significant weight loss increases SHBG levels regardless of diet composition, particularly in women. Cross-sectional studies show that dietary composition is generally not associated with SHBG levels independent of obesity level.​

...
Health Implications

1. Breast Cancer Risk: Increased SHBG levels due to weight loss are associated with a reduced risk of estrogen-sensitive breast cancers in postmenopausal women. This is because higher SHBG levels result in lower levels of free estradiol, which is linked to breast cancer risk.
2. Cardiovascular and Metabolic Health: Higher SHBG levels are beneficial for cardiovascular and metabolic health. They are associated with lower risks of conditions like diabetes and cardiovascular diseases, which are prevalent in obese individuals.

In summary, losing body fat significantly increases SHBG levels, which has various health benefits, including reduced risks of breast cancer, diabetes, and cardiovascular diseases. The degree of weight loss and the method (diet vs. exercise) can influence the extent of these changes.
...

These statements jump from correlation to causality. It's established that higher SHBG is associated with some good things. But where is the evidence that higher SHBG causes them?

 

I should really review the statements made by an AI LOL

 

When I was higher bodyfat I almost felt like my mind and body felt better and more stable.

Higher amounts of body fat means your estrogen will typically be higher.

 

Now we are curious to see lab values...

Calorie and/or carb intake change from baseline (85kg) until now?

 

Higher amounts of body fat means your estrogen will typically be higher.

I think this could be it.

Now we are curious to see lab values...

Calorie and/or carb intake change from baseline (85kg) until now?

I stopped dropping weight a while ago, so have this feeling even with high carbs/calories. Got a test on Friday, but only testosterone, e2 and FBC.

 

In my profile pic, I was a lean 170lbs at 5’6” and had absolutely floored SHBG. I had started losing weight at around 235lbs. I was a skinny kid before puberty, as puberty hit I gained weight, developed gynecomastia, and looked awful while not changing any habits; I ate the same and still raced BMX bikes nearly daily for hours at a time. My theory is a genetically low SHBG causing my issues, but I don’t have any bloodwork as a teen to confirm. For some, SHBG isn’t correlated with weight. Though this is merely my own personal anecdotal evidence.

 

I've found the culprit...

The other day I found that I felt better towards the evening, more typical of my prior TRT experience. I also realized that I had less coffee that day, 2 cups instead of 3. I've seeing something about caffeine and SHBG but didn't think too much into it. Another thing was that I had bought a french press for coffee recently and definitely increased my caffeine intake.

So I had a look at my Amazon and sure enough I could see the purchase was made in mid March, around the exact time this perception of lower testosterone started happening.

Since then I've just had one small weak coffee, probably around 1/6th of what I was having before, perhaps 40-50mg of caffeine rather than 300mg. Sure enough the problem has resolved and I feel good again. I don't have blood work to back this up though.

 

I've found the culprit...

The other day I found that I felt better towards the evening, more typical of my prior TRT experience. I also realized that I had less coffee that day, 2 cups instead of 3. I've seeing something about caffeine and SHBG but didn't think too much into it. Another thing was that I had bought a french press for coffee recently and definitely increased my caffeine intake.

So I had a look at my Amazon and sure enough I could see the purchase was made in mid March, around the exact time this perception of lower testosterone started happening.

Since then I've just had one small weak coffee, probably around 1/6th of what I was having before, perhaps 40-50mg of caffeine rather than 300mg. Sure enough the problem has resolved and I feel good again. I don't have blood work to back this up though.

Hey man, this is interesting! Perhaps an experiment on yourself could paint a picture. Go for your now lowered caffeine intake for 2 months and get labs done. After the labs, increase the intake back to the point you felt worse, run for 2 months then lab it out.

Makes me curious if you found something. I’ve got floored SHBG and it’s likely been a factor since puberty (I developed gynecomastia and a host of other issues during puberty, before coffee lol). Makes me wonder however, if my love of the coffee bean may be a compounding factor. Interesting stuff!

 

We are all different, but diet and exercise have played a role in SHBG levels for me. My SHBG was always low teens for most of my years on TRT. The Last two years I have been on the Keto diet and my SHBG has raised consistently landing between 25-30 Last 4 labs. more than double where it was at for over 5 years. I am not much lighter today, but have changed body composition and am significantly leaner with more muscle lifting 3-4 days a week. 16% body-fat currently.