A new wave of international research reveals that while high-intensity interval training (HIIT) delivers sweeping health benefits, it can also disrupt hormone balance—especially if done too often or without proper nutrition and rest. This has sparked growing interest and concern among fitness buffs and health professionals in Thailand, where HIIT classes and early-morning boot camps are booming. Understanding the nuanced impact of high-intensity exercise on the body’s delicate network of hormones is increasingly important for Thai readers eager to maximize the benefits of their workouts without jeopardizing long-term health or well-being.
Thais, much like global fitness communities, have enthusiastically embraced HIIT for its promise of rapid results. Modern Bangkok gyms, Chiang Mai fitness studios, and even social media influencers frequently spotlight high-impact routines. Yet, new research analyzed in a recent MindBodyGreen report highlights that overdoing HIIT—or performing it under suboptimal conditions—may raise cortisol (the “stress hormone”) and throw other critical hormones like estrogen, progesterone, and testosterone off balance. In turn, this can lead to fatigue, impaired recovery, menstrual disturbances, and, paradoxically, make it harder to shed excess weight.
To make sense of these findings, it’s vital to understand the twin role of exercise: at moderate levels, physical activity triggers the release of mood-lifting and metabolism-boosting hormones, including dopamine, serotonin, insulin, growth hormone, estrogen, and testosterone. Regular activity improves heart health, sharpens the mind, lowers the risk of depression, and can even ease menstrual pain through anti-inflammatory effects driven by progesterone. A 2021 study on HIIT’s effect on testosterone and cortisol in men found that intensive regimens can modulate these hormone levels, influencing everything from performance to recovery.
However, the balance tips when training becomes too frequent, too intense, or is combined with insufficient rest and under fueling. HIIT, by its nature, jacks up cortisol during and shortly after exercise—a necessary adaptation if kept in check. A key meta-analysis referenced in the MindBodyGreen article found that cortisol spikes for 30–60 minutes after HIIT, only bottoming out two hours post-workout and normalizing after 24 hours. In contrast, moderate endurance exercise and resistance training tend to normalize cortisol more quickly.
Leading endocrinologists point out that cortisol, while essential for energy and stress response, becomes harmful when chronically elevated. “Cortisol is an important hormone, so I’m not saying we should try and keep it low,” explains a prominent UK sports endocrinology researcher cited in the report. “But equally, we don’t want to encourage it to be overactive when it’s not needed.” In practice, early-morning HIIT—especially on an empty stomach—is most likely to push cortisol to problematic levels, as natural morning peaks coincide with the added stress of intense training without nutritional support.
Clinical experience underscores this danger: athletes and fitness enthusiasts who repeatedly perform fasted high-intensity sessions often report stalled weight loss, even with strict dieting and heavy training. This “cortisol trap,” as some experts describe it, can trigger the body’s emergency mode—retaining fat stores in anticipation of ongoing stress. Growing evidence from sports science (see Longitudinal study on athletes’ hormonal response) supports the observation that chronic overexercising not only sabotages fat loss but can also lead to a syndrome known as relative energy deficiency in sport (RED-S). Thai sports medicine professionals, particularly those working with the increasing number of runners, cyclists, and group-fitness participants, are starting to see similar trends locally.
Worse yet, elevated cortisol can suppress other hormones. Imbalances can lead to a drop in growth hormone (hindering healthy body composition), lower estrogen and testosterone (risking menstrual irregularities or amenorrhea, and reduced libido or bone density), and even fertility challenges. For women, overtraining is a known cause of amenorrhea, disrupting ovulation and raising long-term risks for osteoporosis, heart disease, and cognitive decline.
These risks are not just theoretical—Thai and regional research is beginning to document similar patterns. An influential Thai-language study on exercise and cortisol in female adolescents found that aerobic exercise programs helped lower both depression and cortisol among students with depressive symptoms, highlighting the mental health benefits of moderate, consistent exercise. However, this benefit relies critically on avoiding chronic overtraining and maintaining proper diet and rest.
Thailand’s shifting fitness landscape makes these findings all the more relevant. The nation’s Ministry of Public Health has set ambitious targets to boost physical activity as part of its National Plan to Promote Physical Activity 2018–2030, but does not currently specify upper limits for high-intensity workouts. Educational outreach must now adapt: while high activity levels are celebrated, the nuances of overtraining and the need for balanced routines deserve more attention in public health messaging, especially as HIIT becomes ever more fashionable.
Local sports scientists, physical therapists, and medical professionals urge moderation and variety. Thai hospital specialists frequently emphasize “rest days” and warn against daily intense classes without proper recovery—echoing international best practices. A leading Bangkok fitness educator recommends rotating HIIT with gentler activities like yoga, Pilates, traditional Thai dance, or even leisurely cycling in public parks. Fueling is equally vital: not just for athletic performance, but for keeping hormones in a healthy range. Dietitians at Thai universities and wellness centers caution against fasted training sessions, particularly for young women and working professionals with irregular meal times.
Moreover, Thailand’s rich cultural heritage offers ready-made solutions. Traditional activities such as Luk Thung dance, Muay Thai forms, and group aerobic classes offer diverse movement options that deliver health benefits without tipping into dangerous cortisol territory (PMC article on traditional Thai dance and stress). These activities are increasingly promoted as part of culturally-appropriate wellness programs, especially in schools and community health settings.
Importantly, balancing high-intensity training with rest and variety is key. As argued by the MindBodyGreen experts and sports endocrinologists worldwide, a well-rounded workout strategy includes:
- Fueling adequately before and after high-intensity sessions, prioritizing carbohydrates for energy.
- Allowing at least one full rest day per week, and varying the type of physical activity performed.
- Paying close attention to signs of overtraining (such as persistent fatigue, sleep problems, stalled progress, or missed menstrual periods).
- Consulting health professionals—especially if using HIIT as part of a weight loss or performance goal, or if there are any stressful life events.
Looking to the future, Thai public health initiatives may increasingly incorporate these findings, perhaps advising on both lower and upper exercise thresholds for different age and risk groups. The country’s ongoing collaboration with the World Health Organization and local institutions positions it well for evidence-based updates to its exercise guidelines. Meanwhile, the fitness industry has a unique opportunity to educate members on balanced routines, respecting the body’s hormonal rhythms.
For the average Thai reader—particularly those who belong to gyms, follow bootcamp trends on TikTok, or aspire to “train like an athlete”—the takeaway is practical and empowering: embrace HIIT and high-impact workouts for their well-documented benefits, but do so mindfully. Mix in low-impact or traditional activities, fuel properly, and never underestimate the value of a day’s rest. If unsure, consult a trusted medical or fitness professional about structuring an exercise program that supports both your ambitions and your overall health.
By personalizing global research for Thailand’s cultural context and rapidly evolving urban lifestyles, the message is clear: exercise should enrich, not exhaust. Wise choices—rooted in science, tradition, and common sense—ensure every workout improves the body inside and out, keeping the intricate balance of hormones working for your long-term benefit.
Sources:
- MindBodyGreen: How High-Intensity Exercise Impacts Cortisol & Other Hormones
- Professional football training and recovery: hormonal response study (2024, PubMed)
- The Effect of High-Intensity Interval Training Periods on Morning Serum Testosterone and Cortisol Levels (2021, PubMed)
- WHO: Thailand’s physical activity drive is improving physical health
- Effects of Exercise Program on Depression and Cortisol Hormone in Female Adolescents (Thai study)
- PMC: Stress reduction through Thai traditional dance