As we've discussed previously there are a number of ways that the metabolism will adapt throughout the process of dieting and losing weight.
Today we're diverting our attention to looking at more of the hormonal shifts that take place during the different phases of a diet that can have an impact on everything from water retention thats masks real fat loss all the way down to your ability to recover from exercise.
“Metabolic Damage” Is Actually An Adaptation…
There’s a specific component of your BMR that has very little to do with your weight, or the amount of weight you’ve lost.
This adaptation in BMR is more of a hormonal response to a calorie deficit, and while you and I both know you’re not really starving to death when you diet, your body doesn’t know the difference between long period of low calories and slow starvation.
Because your body is intelligent and wants to keep you alive for as long as possible it finds ways to become more efficient and conserves more calories.
Most people would think the answer is to diet harder, but unfortunately that only causes the metabolism to adapt to an even greater degree to match calorie intake by lowering calorie expenditure even further.
Your body real doesn’t want you to maintain very low levels of body fat and will push back against this fat loss to return you to a state of balance by increasing your hunger hormones, making you more lethargic and sluggish and lowering your calorie burn at rest or during exercise.
The Hormonal Responses
When you create a calorie deficit for fat loss to happen there’s going to be hormonal shifts that coincide with how aggressively you’re dieting.
If you got on a really low calories right away your hormones are going to make a much larger shift than if you took a slow and steady approach to dieting.
The main hormones affected by your dieting are going to be thyroid hormones, sex hormones and stress hormones such as cortisol.
We’re going to look at these hormones but I am not an endocrinologist and if you suspect you are dealing with hormonal dysregulation please seek out a professional and get the right tests done instead of reading a blog or newsletter on the topic.
The main thyroid hormones we’re concerned with during the process of dieting are T4 (Thyroxine) and T3 (Triiodothyronine).
T4 is the inactive version of the thyroid hormone almost considered a pro- hormone, that only works when it’s converted to the active T3 hormone.
What is really important is that the concentration is equally as important as the conversion of the hormones, and dieting shows to cause a decrease in the active and usable thyroid hormone T3 which downshifts thyroid function.
Dieting on too low of calories for too long with excessive exercise will also cause an increase in the stress hormone cortisol. This is not a good or bad hormones, but too much can cause some problems. When cortisol is chronically elevated it interferes, and hinders the conversion of the T4 to T3.
If you’re interested in a much more in depth breakdown of thyroid function, and the different hormones let me know.
It is a very complicated gland and is tied to regulating a number of different functions in the body that span beyond what’s necessary for this blog.
Stress Hormone: Cortisol
You’ve likely heard some of the negative aspects of the stress hormone cortisol it’s not a “bad’ hormone in fact we need this hormone like all others in a specific balance.
The poison is in the dose with cortisol.
We need cortisol to help with muscle inflammation, provide energy, manage a stress response and even mood improvement.
However when you place too many external stressors on your body and lack the capacity to recover from them that’s when excess cortisol gets released and create dysfunction.
Stress is stress and comes from a number of different places such as emotional and psychological stressors, physical stressors like dieting too aggressively in combination with excess cardio and weights.
As mentioned above this excess cortisol can interfere with thyroid function by reducing the conversion of T4 to T3.
Excessive cortisol circulating due to training like a bat out of hell on lower calories can cause water retention, and mask their true fat loss.
If you’re losing body fat, but you’re also retaining an extra 3-5 pounds of water because of stress then you may see no changes on the scale even though you’re actually losing fat, which can be maddening for people at times.
Carbohydrates are the best macronutrient to blunt the effects of cortisol which is why sometimes people will take a higher carb day and wake up lighter on the scale and leaner in the mirror.
Stay tuned for next week when we discuss the relationship aggressive dieting has to the hormone leptin and the sex hormones!