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TOPIC: Does exercise increase cortisol in everybody?

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August 12, 2012 3:11 AM
Ok, so I am a bit confused. Lately I have been reading a few books and hearing from other people that I should limit my exercise to 45 minutes per day. Apparently because it elevates cortisol if I do more exercise than this per day, it will defeat the purpose and I won't lose weight.
But here's the thing.... I have always struggled to lose weight even with normal diet and exercise. I won't go into detail but I have a metabolic disorder that makes it more difficult. So in the past I have exercised a lot to counteract this and it has worked for me. But the last couple months I have been doing this and it's not working anymore.
I like to exercise, I don't mind doing a few hours a day of multiple activities like walking, cardio dance, and strength training dvds. It really doesn't exhaust me or seem to put a lot of stress on my body, because even though I'm overweight I'm still in pretty good shape.
So my question is, for people like me who are used to exercising for a few hours a day on a normal basis, do cortisol levels still go up and stall weight loss? I'm really confused about this, so if someone could help me out I would appreciate it.
August 12, 2012 3:25 AM
cortisol may have an effect on how fat is stored. However I don't think it's true that exercise increases cortisol, I think it decreases it. And cortisol won't stop you from losing weight if you are in a calorie deficit.

I have PTSD which means I have far to much of the stress hormones (adrenaline and cortisol) in my system. It hasn't stopped me from losing weight and my counsellor has always encouraged me to exercise because it reduces the amounts of stress hormones in the system and replaces them with "happy" hormones like endorphines. If it's had any effect then maybe it explains why I tend to store fat around my waist but I'm combatting that through exercise and healthy eating.

It may be the case that if you are overtraining this puts a lot of stress on the body and that may affect cortisol but you really have to do a LOT of exercise before you get overtraining problems. I don't think 45 mins per day is excessive at all, and I'd advise you to do weight training as well as cardio if you're not already, because it improves your body composition more. If you're undereating and doing too much cardio then you may have slowed your metabolism but I don't think cortisol has a lot to do with it. The way to fix that is to eat at a small deficit (e.g. 15% less than your TDEE) and do less cardio and more weights. It may even benefit you to eat all your TDEE calories for a while, while doing weight training, to really boost your metabolism, then dropping to a small deficit and continuing with the weight training.

If you are eating enough to sustain the level of exercise you're doing, taking some rest days and also not suffering from any signs of undereating/overtraining then I wouldn't worry about it. It all depends on whether you are eating enough because undereating and too much exercise puts all kinds of stress and strain on the body, and you'd have more to worry about than cortisol. However if you're eating properly (i.e. all food groups, enough calories, enough protein etc) then your body is made to exercise and if it wasn't able to take more than 45 mins exercise a day then the human race would not have survived!!
Edited by dhakiyya On August 12, 2012 3:25 AM
August 12, 2012 3:30 AM
Training Effects
Because cortisol is released in response to stress, exercise training will increase the threshold of cortisol release. For example, if you begin an exercise program walking at a 20-minutes per mile pace, cortisol will be released at that intensity. However, as your training progresses and you begin walking at a 15-minutes per mile rate, the body will not perceive the 20-minutes per mile pace to be as stressful and will not release as much cortisol. Additionally, the time and intensity of exercise will dictate the level of cortisol release. If you exercise for more than 60 minutes, even at a low intensity, the body's glycogen stores (fuel) will decrease significantly and the increased stress will cause more cortisol release. The more training you do, the better your body will become at dealing with physical stresses and decrease the need to release cortisol. This effect is not limited to exercise; people who are regularly active show a decreased cortisol response to an emotional crisis when compared to sedentary controls.

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August 12, 2012 3:31 AM
great post! thank you!
August 12, 2012 3:52 AM
Cortisol is a hormone released during stress, so the more strain you put on your body, the higher it'll get. However there is a difference between exercise related cortisol and stress(mood) related cortisol. Exercise also stimulates growth hormones, endorphin, testosterone, estrogen, T3, epinephrine, the list goes on. Almost all of them has positive effect on fat metabolism and you won't get them up to those levels in a sedentary life. Plus, it is very easy to decrease blood cortisol levels for a healthy adult. It's called a good night sleep.

ETA: Sleep deprivation will cause far more stress hence higher cortisol levels especially during evening compared to an hour of medium intensity workout.

Each subject (n = 6) performed a 1-min bout of exercise on a cycle ergometer at 120% of his maximum O2 uptake. Blood samples were collected at rest, immediately following the exercise bout, and at 5, 15, and 30 min postexercise. Mean (+/- SE) plasma ACTH levels increased significantly (P less than 0.05) from 2.2 +/- 0.4 pmol/l at rest to 6.2 +/- 1.7 pmol/l immediately following exercise. Mean (+/- SE) plasma cortisol levels increased significantly from 0.40 +/- 0.04 mumol/l at rest to 0.52 +/- 0.04 mumol/l at 15 min postexercise.

The percent change in cortisol from pre- to post-sampling at each session was: resting-control, 40, 60, and 80% sessions (mean+/-SD) =-6.6+/-3.5%, +5.7+/-11.0%, +39.9+/-11.8%, and +83.1+/-18.5%, respectively. The 60% and 80% intensity magnitude of change was significantly greater than in the other sessions, as well as from one to another. The ACTH responses mirrored those of cortisol, but only the 80% exercise provoked a significant (p<0.05) increase pre- to post-exercise. The calculated changes in plasma volume for the resting-control, 40%, 60%, and 80% sessions were: +2.2+/-3.0%, -9.9+/-5.0%, -15.6+/-3.5%, and -17.2+/-3.3%, respectively. Collectively, the cortisol findings support the view that moderate to high intensity exercise provokes increases in circulating cortisol levels.
Edited by xarge On August 12, 2012 3:55 AM

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