symptom-contingent pacing, in which the decision to stop (and rest or change an activity) is determined by self-awareness of an exacerbation of symptoms, and time-contingent pacing, which is determined by a set schedule of activities that a patient estimates he or she is able to complete without triggering post-exertional malaise (pem). thus, the principle behind pacing for cfs is to avoid overexertion and an exacerbation of symptoms. it is not aimed at treating the illness as a whole. those whose illness appears stable may gradually increase activity and exercise levels, but according to the principle of pacing, must rest or reduce their activity levels if it becomes clear that they have exceeded their limits. use of a heart-rate monitor with pacing to monitor and manage activity levels is recommended by a number of patient groups, and the cdc considers it useful for some individuals to help avoid post-exertional malaise. energy envelope theory energy envelope theory, considered to be consistent with pacing, is a management strategy suggested in the 2011 international consensus criteria for me, which refers to using an "energy bank budget". energy envelope theory was devised by psychologist leonard jason, who previously had cfs. energy envelope theory states that patients should stay within, and avoid pushing through, the envelope of energy available to them, so as to reduce the post-exertional malaise "payback" caused by overexertion. this may help them make "modest gains" in physical functioning. several studies have found energy envelope theory to be a helpful management strategy, noting that it reduces symptoms and may increase the level of functioning in cfs. energy envelope theory does not recommend unilaterally increasing or decreasing activity and is not intended as a therapy or cure for cfs. it has been promoted by various patient groups. some patient groups recommend using a heart rate monitor to increase awareness of exertion and enable patients to stay within their aerobic threshold envelope. despite a number of studies showing positive results for energy envelope theory, randomized controlled trials are lacking. exercise stretching, movement therapies, and toning exercises are recommended for pain in patients with cfs. in many chronic illnesses, aerobic exercise is beneficial, but in chronic fatigue syndrome, the cdc does not recommend it. the cdc states:any activity or exercise plan for people with me/cfs needs to be carefully designed with input from each patient. while vigorous aerobic exercise can be beneficial for many chronic illnesses, patients with me/cfs do not tolerate such exercise routines. standard exercise recommendations for healthy people can be harmful for patients with me/cfs. however, it is important that patients with me/cfs undertake activities that they can tolerate... counseling chronic illness can impact mental health, and depression or anxiety resulting from me/cfs is common. psychotherapy may help patients manage the stress of being ill, apply self-management strategies for their symptoms, and cope with physical pain. however, treating co-occurring anxiety or depression will not cure me/cfs, and talk therapy should not be undertaken in an attempt to cure me/cfs. nutrition a proper diet is a significant contributor to the health of any individual. medical consultation about diet and supplements is recommended for persons with cfs. persons with cfs may benefit from a balanced diet and properly supervised administration of nutritional support if deficiencies are detected by medical testing. risks of nutritional supplements include interactions with prescribed medications. treatment there are no approved treatments for me/cfs. cognitive behavior therapy (cbt) and graded exericse therapy (get) have been proposed, but their safety and efficacy are disputed. the drug rintatolimod has been trialed and has been approved in argentina. cognitive behavioral therapy cognitive behavioral therapy for me/cfs is a variant of cbt that assumes a cognitive-behavioral model of me/cfs. in this model, people with me/cfs mistakenly attribute their illness solely to physical causes, and their condition is perpetuated by a fear of triggering symptoms, which leads to a vicious cycle of deconditioning and avoidance of activity. cbt aims to help patients view unhelpful thoughts and behaviors as factors in their illness. this model has been criticized as lacking evidence and being at odds with the biological changes associated with me/cfs, and the use of this type of cbt has been the subject of much controversy. nice removed their recommendation for this form of cbt in 2021, replacing it with a recommendation to offer patient cbt for help coping with distress that illness causes. the guidelines emphasize that cbt for people with me/cfs should not assume that unhelpful beliefs cause their illness, and should not be portrayed as curative. similarly, the cdc stopped recommending cbt as a treatment in 2017, recommending counseling as a coping method instead. a 2015 national institutes of health report concluded that while counseling and behavior therapies could produce benefits for some people, they may not yield improvement in quality of life, and because of this limitation such therapies should not be considered as a primary treatment, but rather should be used only as one component of a broader approach. this same report stated that although counseling approaches have shown benefit in some measures of fatigue, function and overall improvement, these approaches have been inadequately studied in subgroups of the wider cfs patient population. further concern was expressed that reporting of negative effects experienced by patients receiving counseling and behavior therapies had been poor. a report by the institute of medicine published in 2015 states that it is unclear whether cbt helps to improve cognitive impairments experienced by patients.: 265 a 2014 systematic review reported that there was only limited evidence that patients increased levels of physical activity after receiving cbt. the authors concluded that, as this finding is contrary to the cognitive behavioural model of cfs, patients receiving cbt were adapting to the illness rather than recovering from it. in a letter published online in the lancet in 2016, charles shepherd, medical advisor to the me association, expressed the view that the contention between patients and researchers lay in "a flawed model of causation that takes no account of the heterogeneity of both clinical presentations and disease pathways that come under the umbrella diagnosis of me/cfs". a 2020 systematic review did not find cbt to be effective. while most studies claimed positive results, overall evidence quality was low. the use of subjective outcomes in non-blinded trials rendered the results prone to bias, and adverse effects were not reported. when objective outcomes were used, improvements were not seen. further, the reviewers concluded that the applicability of these studies to modern patient cohorts was dubious because all the studies analyzed used the older oxford of fukuda criteria, which did not require pem. a 2022 evidence review contracted by the cdc found weak evidence supporting a small to moderate positive effect for cbt.: 23 patient organisations have rebuffed the use of cbt as a treatment for cfs to alter illness beliefs. the me association recommended in 2015, based on the results of an opinion survey of 493 patients who had received cbt treatment in the uk, cbt in its current form should not be used as a primary intervention for people with cfs. in 2019, a large uk survey of people with me/cfs reported that cbt was ineffective for more than half of respondents. graded exercise therapy main article: graded exercise therapy graded exercise therapy (get) is a programme of physical therapy that starts at a patient's baseline and gradually increases over time. like cbt, it assumes that patients' fears of activity and deconditioning play a significant role, and its safety and efficacy are debated. the 2021 nice guidelines removed get as a recommended treatment due to low quality evidence regarding benefit, with the guidelines now telling clinicians not to prescribe "any programme that ... uses fixed incremental increases in physical activity or exercise, for example, graded exercise therapy." the cdc withdrew their recommendation for get in 2017. a 2022 review contracted by the cdc found that get may produce small to medium improvements in fatigue, functioning, depression, anxiety, and sleep, based on weak evidence. the authors concluded that trials suffered from methodological limitations, had limited reporting of harms, and generally enrolled patients based on older definitions of me/cfs that do not require pem. the cdc does not recommend get, and there is some evidence of harm. a 2019 updated cochrane review stated that exercise therapy probably has a positive effect on fatigue in adults, and slightly improves sleep, but the long-term effects are unknown and relevance to current definitions of me/cfs is limited. cochrane started re-evaluating the effects of exercise therapies in chronic fatigue syndrome in 2020. an independent re-analysis of the same studies as the cochrane review concluded that get is ineffective and there was no evidence of safety, citing the risk of bias in non-blinded trials with subjective outcome measures, the use of broad inclusion criteria, potential problems with the questionnaires used, and inconsistent dropout rates. a 2020 systematic review found that get was not shown to be effective, due to the low quality and high risk of bias of trials. none of the studies analyzed used a definition of me/cfs that required pem, and few reported adverse effects. the main outcomes were self-reported and subjective, which may create bias when blinding is impossible. patient organisations have long criticised the use of exercise therapy, most notably get, as a treatment for me/cfs. based on an opinion survey of patients who had received get, in 2015 the me association concluded, get in its current delivered form should not be recommended as a primary intervention for persons with me/cfs. adaptive pacing therapy apt, not to be confused with pacing, is a therapy rather than a management strategy. apt is based on the idea that cfs involves a person only having a limited amount of available energy, and using this energy wisely will mean the "limited energy will increase gradually".: 5 a large clinical trial known as the pace trial found apt was no more effective than usual care or specialized medical care. the pace trial generated much criticism due to the broad oxford criteria patient selection, the standards of outcome effectiveness being lowered during the study, and re-analysis of the data not supporting the magnitude of improvements initially reported. unlike pacing, apt is based on the cognitive behavioral model of chronic fatigue syndrome and involves increasing activity levels, which it states may temporarily increase symptoms. in apt, the patient first establishes a baseline level of activity, which can be carried out consistently without any post-exertional malaise ("crashes"). apt states that persons should plan to increase their activity, as able. however, apt also requires patients to restrict their activity level to only 70% of what they feel able to do, while also warning against too much rest. this has been described as contradictory, and jason states that in comparison with pacing, this 70% limit restricts the activities that patients are capable of and results in a lower level of functioning. jason and goudsmit, who first described pacing and the energy envelope theory for cfs, have both criticized apt for being inconsistent with the principles of pacing and highlighted significant differences. apt was promoted by action for me until 2019. action for me was the patient charity involved in the pace trial. rintatolimod rintatolimod is a double-stranded rna drug developed to modulate an antiviral immune reaction through activation of toll-like receptor 3. in several clinical trials of cfs, the treatment has shown a reduction in symptoms, but improvements were not sustained after discontinuation. evidence supporting the use of rintatolimod is deemed low to moderate. the us fda has denied commercial approval, called a new drug application, citing several deficiencies and gaps in safety data in the trials, and concluded that the available evidence is insufficient to demonstrate its safety or efficacy in cfs. rintatolimod has been approved for marketing and treatment for persons with cfs in argentina, and in 2019, fda regulatory requirements were met for exportation of rintatolimod to the country. prognosis information on the prognosis of cfs is limited, and the course of the illness is variable. according to the nice guideline, cfs "varies in long-term outlook from person to person." complete recovery, partial improvement, and worsening are all possible. symptoms generally fluctuate over days, weeks, or longer periods, and some people may experience periods of remission. overall, "many will need to