STEP 2A. How to Increse Cortisol If You Are Low:
One of the very common issues that I see on the The Peak Testosterone Forum is extreme fatigue. Of course, there can be many reasons for this: low testosterone, nutritional deficiencies, sleep disorders, gut issues, hypothyroidism, blood glucose / insulin issues, etc. But one of the most overlooked and surprisingly common causes of fatigue is low cortisol, and this is because many men do not even realize that low cortisol is possible in our stressed out, fast-paced lives. They assume that high cortisol is the norm and do not recognize some of the standard low cortisol symptoms such as dizziness, joint aches, heart palpitations, weakness, anxiety, etc. As always, I recommend pulling your numbers and you can do that (if you are in the U.S. and in the U.K:) here: Inexpensive Testosterone Labs.
Another group of men that can end up with low cortisol are men on testosterone therpay. This can be a side effect for some men on HRT (TRT) due to a partial "shutdown" process. I don't know of any studies out there providing evidence for that phenomenon, but it is definitely reported and may be one of the reasons for HRT failure in some men. Therefore, it is probably prudent for men taking testosterone to regularly monitor their cortsiol, something they can do at the above link.
The big question is this: if you find that you have low cortisol and standard low cortisol symptoms, how do you naturally raise your cortisol levels? Below I list The Three Most Common Ways to Try to Increase Cortisol:
CAUTION: If you have low cortisol, I always recommend that you work with a knowledgeable physician. In addition, all three of the methodologies below are best tested and implemented with a knowledgeable physician or naturopath:
1. Low Dose Hydrocortisone (Cortef usually). This is one of the most powerful, yet most controversial solutions for raising cortisol levels. First of all, the benefits can easily be as impressive as TRT for many men. You can give hydrocortisone and see profoundly positive changes in some men. They will feel better almost right away with fatigue vanishing and energy level returning, etc. It can be a real life saver, at least in the short term, for many men out there.
I cover the classic, must read book on the subject here: Low Dose Cortisol Replacement Therapy as covered in Safe Uses of Cortisol by Dr. Willaim Jeffries. This book will answer most of your questions about the use of small dosages of hydrocortisone to replace cortisol. (Cortisol is actually converted to hydrocortisone in the body.)
Furthermore, proponents of this approach (when diagnosed appropriately of course) - and they include some big online names such as Drs. Crisler, Shames, Mariano, etc. - insist on only using low dose hydrocortisone. Low dose is generally defined between 5 and 20 mg / day and is considered physiological and not supposed to result in much of a shutdown. Some doctors will go up to about 40 mg/day The duration of therapy is variable: some of the doctors try to only use hydrocortisone for a few weeks, say 6-8, and others allow indefinite use.
NOTE: Dosages often start with 5 or 10 mg in the morning and then 5 mg is added after a week if no improvement is noted. Common protocols I have seen are 10 mg in the morning and 10 in the evening or 10 - 5 - 2.5 - 2.5 mg at 6-8 hour intervals. Again, discuss with your doctor and to read more about the subject, see Dr. Shames' pioneering book on adrenal fatigue Feeling Fat, Fuzzy, or Frazzled?. (I'm not a big fan of adrenal fatigue theory, but this book is packed with helpful information.)
POTENTIAL LONG TERM ISSUES: Dr. Scally has probably been the most vocal critic of this type of protocol and has outlined his concerns in a thread here. The thread is long - definitely worth the read sometime - and so I have summarized his concerns below::
a) Osteoporosis. One study looked at hydrocortisone given in the 20-30 mg/day range and found that "a high proportion of patients on conventional corticosteroid replacement therapy are over treated or on inappropriate replacement regimens. To reduce the long term risk of osteoporosis, corticosteroid replacement therapy should be individually assessed and over replacement avoided."  Dr. Scally then quotes out of a study that is very clear that ""physicians gave a daily dose of 7.5 mg or more of prednisolone as the threshold at which one should be concerned about fracture risk, whereas more recent studies clearly indicate a substantial risk in individuals taking between 2.5 and 7.5 mg daily, a risk that was significantly higher than individuals taking a low dose (2.5 mg daily or less) for nonvertebral fracture, hip fracture or vertebral fracture." 
This singificance of this is 2.5 mg and 7.5 mg of prednisolone is the equivalent of 10 and 30 mg of hydrocortisone daily and basically this review is saying, therefore, that anything over 10 mg/day puts you at an increased risk of fractures. 30 mg/day greatly (more than doubles) your risk of fracture.
b) Memory and Psychological Issues.
Again, there are studies to back up these very serious concerns.
REBUTTALS: In spite of the research that outlines very serious problems with hydrocortisone, there is literally an underground community, if you will, that have actively experimented with and implemented low dose therapies. They feel that the concerns are grossly overstated:
a) Field Experience. The counterargument to the above is that Dr. Jeffries - the originator of the low dose hydrocortisone protocols - developed his treatment plan for those with low cortisol and accompanying fibromyalgia, arthritis and certain other medical conditions. And, anecdotally, some in these communities have been taking low dose hydrocortisone for years supposedly without issues. Furthermore, some doctors and big sites such as Stop the Thyroid Madness have backed this protocol. And, if you want to read Dr. Jeffries original book that started it all, check it out here: Safe Uses of Cortisol.
Ray Peat argued forcefully, though, against some of the higher dosages in Dr. Jeffries "low dose" protocol:
"The doses they prescribe as "replacement" are much more than the adrenals would produce, so they in themselves are diabetogenic. William Jefferies told people that, since the adrenals produce 20 mg of cortisol per day, they should take 30 or 40 mg, as a replacement dose, because only half of it is absorbed. They got fat faces quickly. Using pregnenolone, they were able to taper off the cortisol in a month or two." 
b) Restart. Some men seem to be able to restart their cortisol production, ironically, with low dose hydrocortisone. Of course, what this means is that, in this case, hydrocortisone can be used successfully only on a short term basis. Still other men may be able to get by the regular cycling?
The bottom line is that there is little data and one probably has to rely on the input from a physician as to a proper protocol and application in order to make sure you don't have long term issues.
NOTE: Some thyroid patients state that low cortisol patients often need a little hydrocortisone to "push" the thyroid hormones intracellularly. From a functional medicine perspective, this is correct and appears to be backed by many anecdotal reports. Of course, this means that some thyroid patients are likely not experiencing good success due to their low cortsiol.
2. Licorice Extract. This is another controversial solution to boost cortisol. One reads reports of men taking licorice extract with dramatic improvements in things like fatigue and mental fog probably due to a boost in cortisol. It works by "the active metabolites in licorice extract which are glycyrrhizic acid and glycyrrhetic acid can lead to a syndrome known as apparent mineralocorticoid excess. These side effects arise from the inhibition of the enzyme 11- -HSD and subsequent increase in the activity of cortisol."  Because licorice is consumed as a food and and has been used nutraceutically for peptic ulcers and Addison patients, considerable research has gone into safe levels. There are differing views on the subject as you can see from this excerpt below:
"The main difficulty with licorice dosing lies in its availability in various forms such as candies, beverages, supplements and extracts that contain different amounts of the active components of licorice. In the United States, the manufacture of some dietary supplements, including licorice, is not closely regulated. In 1991, the European Union proposed a provisional figure of 100 mg/day as the upper limit for ingestion of glycyrrhizin (approximately the amount found in 60 70 g licorice). In April 2003, the Scientific Committee on Food confirmed an upper limit of 100 mg/day. This was based on data from human volunteer studies." 
Why are researchers so concerned? There are two primary side effects observed: hypertension and muscle weakness. I would add a third as well: potentially lowered testosterone levels.  Consider the serious drop in testosterone that occurred by giving men 7 g daily of a of licorice containing 0.5 g of glycyrrhizic acid : participants went from 740 ng/dl (day 0) to 414 ng/dl (day 4) and 484 (day 7). Those are drops of 44% and 35%, respectively!
So, while one could argue "any port in a storm," keep in mnd that some would label licorice an actual "endocrine disruptor" and that's not a bad term considering the drop in T mentioned above. This would be especially true if you are already hypogonadal.
REBUTTAL: Proponents of licorice argure that this is a widely used food, has relatively low side effects and can make a night and day difference for some people. Let me just relate one story out there that I came across on the web from a man who complained of anheonia, i.e. an inability to feel pleasure.
"Also I knew it wasn't just the sex drive, I never got excited, I never got thrilled, I never got scared, goosebumps or heavy sweating. I used to be quite nervous and sweat alot, all this had gone. As we both know norepinephrine plays a massive part, its just about how do we get the adrenal glands working again. LICORICE ROOT ITS THE NEXT BEST THING TO A MIRACLE!!!!!!!!!! I am being 100% serious, thank God, I really thought I was stuck in a life of anhedonia, with no hope. just lay there with no feelings, no enjoyment. Just feeling very flat and cold. But now its back, sorry to be graphic but i feel like my testicles are alive again, i feel very sexual, its like when you are full of adrenaline the testes are filled with life and so is the brain. I think it has to do with adrenaline and noradrenaline. When I am nervous my heart now races once again, I can sleep easily through the night and love my sleep, I also enjoy exercising and being active. This is a gift a gift of the highest order. It is adrenaline and noradrenaline that drives our brains and our bodies." 
Licorice also has some other nice properties: it can suppress appetite and fights H. Pylori as well. And, as with hydrocortisone, some practitioners urge tapering off one's licorice dose in order to completely get off of it.
3. Pregnenalone or Progesterone. Many men want to raise cortisol more "naturally" by using one of these two hormones. The theory is this:
a) Some men have a dysfunctional cortisol production pathway due to aging, etc.
b) By taking a hormone that is farther upstream, the body can then backfill the appropriate downstream hormones based on the need
c) If the body is low in cortisol and you provide more upstream "hormonal substrate," the body will then make sure that cortisol is replenished via a "trickle down effect
Does it really work this smoothly? Not on your life! Yes, it does happen, but not with any consistency or reliability from what I have seen. As you know, theory and practice are often widely divergent. And what few studies there are out there show the same thing. For example, one set of authors noted that "we have previously found that pregnenolone is preferentially metabolized to allopregnanolone, rather than other compounds such as cortisol or DHEA."  Counterintuivitely, allopregnenalone oftenactually lowers cortisol.  (Allopregnenalone is anti-anxiety, so that makes some sense.)
CONCLUSION: You can try supplementing with pregnenalone or progesterone, and you may be one of the fortunate ones. Furthermore, both of these have other excellent properties that can really help some men in and of themselves. See my Summary Page on Pregnenalone and Progesterone for more information. I would add, though, that I always recommend when it comes to hormones to a) test yourself first and b) work with a physician, naturopath or perhaps Life Extension Foundation.
1) Clin Endocrinol (Oxf). 1997 Mar;46(3):255-61. Glucocorticoid replacement therapy: are patients over treated and does it matter?
2) Eur J Endocrinol, 2011 Nov;165(5):761-9, "Grapefruit juice and licorice increase cortisol availability in patients with Addison's disease", http://www.ncbi.nlm.nih.gov/pubmed/21896619
3) Health Technol Assess, 2007 Mar, 11(7), "Glucocorticoid-induced osteoporosis: a systematic review and cost-utility analysis"
4) Biol Psychiatry, 2013 Jun 1, 73(11): 1045 1053, "Allopregnanolone Elevations Following Pregnenolone Administration are Associated with Enhanced Activation of Emotion Regulation Neurocircuits"
5) Exp Clin Psychopharmacol, 2010 Feb, 18(1): 78 86, "Effects of acute progesterone administration upon responses to acute psychosocial stress in men"
6) Endocrinologia Japonica, 1988, 35(2):333-342, "Inhibitory effect of glycyrrhetinic acid on testosterone production in rat gonads."
7) Steroids. 2004 Oct-Nov, 69(11-12):763-6, "Licorice reduces serum testosterone in healthy women"
8) Ther Adv Endocrinol Metab, 2012 Aug, 3(4): 125 138, "Licorice abuse: time to send a warning message"
9) N Engl J Med, Oct 7 1999; 341:1158, "Reduction of Serum Testosterone in Men by Licorice"