How to optimize hormone health through sleep, stress, and training

Originally published on February 22, 2023

Hormone health shapes sleep quality, body composition, recovery, appetite, and exercise performance, and this guide explains which daily habits influence it most. In Episode 210 of the WHOOP Podcast, Global Head of Human Performance, Principal Scientist at WHOOP Kristen Holmes speaks with Dr. Kyle Gillett, a dual board-certified physician in family medicine and obesity medicine, about the link between hormones and everyday behavior.

Gillett breaks the topic into practical levers: exercise, nutrition, sleep, stress, sunlight, and a sense of purpose. He explains what hormones actually do, why sleep loss can affect testosterone and growth hormone output, how protein and meal timing change satiety, and which supplements he uses most often in practice.

To listen to Episode 210 of the WHOOP Podcast in full, head to the WHOOP Podcast on YouTube.

What do hormones actually control in the body?

Hormones help the body coordinate nearly every major process, from heart rate and metabolism to reproduction, sleep, and appetite. Gillett describes them as signaling molecules, which means they tell cells what to do and when to do it.

He separates hormone signaling into three buckets. Endocrine hormones send signals throughout the body. Paracrine hormones act more locally between nearby cells. Autocrine hormones act within the same system, which matters during exercise because muscle tissue uses local signals to drive adaptation. That framework makes it easier to understand why hormone health extends far beyond testosterone or estrogen.

The conversation also widens the usual definition of hormones. Gillett points to thyroid hormone, cortisol, prolactin, growth hormone, insulin, dopamine, norepinephrine, epinephrine, and even vitamin D. Thyroid hormone, for example, influences how quickly cells can break down and use fat for fuel, and it can affect resting heart rate. That is one reason trends in WHOOP metrics such as resting heart rate and HRV can act as useful context when something in the body feels off.

Hormonal shifts can also sit at the center of common life stages and conditions. Menopause is one of Gillett's clearest examples because ovarian estrogen and progesterone production changes in a way that can alter body composition, sleep quality, and genitourinary symptoms. If that topic is top of mind, How to Support Your Body Through Menopause with Dr. Jessica Shepherd offers a useful next layer.

Gillett puts the definition plainly:

“Hormones are the literal signaling molecule.”

What you should take away

• Hormones influence metabolism, heart rate, sleep, reproduction, appetite, and exercise adaptation.
• Hormone signaling includes endocrine, paracrine, and autocrine pathways.
• Thyroid hormone, cortisol, insulin, growth hormone, dopamine, and vitamin D all belong in the hormone conversation.
• Changes in resting heart rate and HRV can add context when a hormonal issue is affecting recovery or daily function.

If you want to hear Gillett unpack how hormones act as signaling molecules across the body, listen to the full episode on Youtube.

How does exercise support hormone health and body composition?

Once hormones are framed as the body's communication system, exercise becomes one of the clearest daily inputs into that system. Gillett's answer is simple: lift weights, build aerobic capacity, and choose forms of movement you can keep doing for years.

His first principle is that everyone should have a movement practice that can last a lifetime. Enjoyment matters because consistency matters. From there, resistance training takes priority for people with low lean body mass, low bone mineral density, sarcopenia, osteopenia, or osteoporosis. Gillett highlights postmenopausal women as a group that often benefits from more resistance work, especially axial loading exercises such as squats and deadlifts.

He also makes the case for starting as simply as needed. For beginners, bodyweight movements can be enough to begin building capacity. When more detail is useful, body composition tools such as DEXA or BOD POD can help show whether low lean mass or low bone density should change the training emphasis.

A second theme is that cardio still matters. Zone 2 work supports mitochondrial function and better aerobic fitness, and Gillett says even 60 to 90 minutes per week is a solid baseline. He also argues for short bouts of very hard effort, roughly once a week, because maximum effort work pushes a different part of the fitness system. That can mean a few hard 200 meter sprints, or several short intervals with full recovery.

Where people run into trouble is fast weight loss. Gillett says people who cut body weight too quickly often lose lean mass along with fat, and that can lower metabolic rate and make it harder to maintain progress. His practical answer is slow weight loss, enough protein, and resistance training at least three times per week for major muscle groups.

As Gillett explains:

“Lower lean body mass is going to lead to a lower metabolism, is going to lead to more metabolic dysfunction and more body fat accrual.”

What you should take away

• Resistance training helps preserve lean mass and bone density, which supports metabolism and long term function.
• Bodyweight exercises can be an effective entry point for people who are new to strength training.
• Zone 2 work and brief maximum effort intervals support different parts of hormone related fitness and recovery.
• Slow weight loss, combined with lifting and enough protein, helps protect lean body mass.

If you want to hear Gillett go deeper on resistance training, zone 2, and lean mass, listen to the full episode on Youtube.

How should you eat to support hormone balance and exercise performance?

Training changes the body's demands, and food determines whether those demands are met well. Gillett's default approach is a balanced diet that includes carbohydrate, fat, and protein, then adjusts the mix based on body composition goals, activity level, and life stage.

For people in a calorie deficit, he puts special attention on dietary fat. Gillett says higher fat intake, even within isocaloric diets, can help preserve total testosterone during a fat loss phase. He also warns against eliminating carbohydrate entirely, because very low carbohydrate intake can lower free testosterone and raise sex hormone binding globulin, or SHBG, which binds and carries sex hormones in the blood. His practical rule is to keep some carbohydrate around exercise so training and recovery both have support.

Protein gets even more attention. Gillett recommends at least 0.7 grams of protein per pound of body weight per day for the average person. During heavy training, or in older adults trying to hold onto muscle, he says intake can rise to 1 gram per pound. That echoes a broader WHOOP conversation about sex differences in fueling, including Dr. Stacy Sims on nutritional differences between men and women and How to Train Through All Phases of Life.

He also breaks down satiety by macronutrient. Carbohydrate can trigger a quick satiety signal, then fade quickly. Protein takes longer to signal fullness, but lasts longer. Fat moves more slowly still. For many people, that means protein helps keep hunger steadier across the day. Gillett links part of that response to GLP-1, a hormone involved in satiety and glucose regulation.

Meal timing matters too. Gillett leans toward more animal based protein earlier in the day, then more plant based protein later in the day, especially in shakes. His reasoning is practical. Earlier protein supports muscle protein synthesis and exercise recovery, while a lighter plant based emphasis in the evening may fit better with sleep and overnight metabolic regulation. People who want another meal timing discussion can read Dr. Hazel Wallace on nutrition and habit formation and Science of Training and Sleeping Based on Your Menstrual Cycle.

Gillett gives a clear target:

“For the average person, get at least 0.7 grams per pound of body weight per day.”

What you should take away

• A balanced intake of carbohydrate, fat, and protein is Gillett's starting point for hormone health.
• Dietary fat can help preserve total testosterone during a calorie deficit.
• Very low carbohydrate intake can lower free testosterone and raise SHBG in some people.
• Daily protein intake of at least 0.7 grams per pound of body weight is Gillett's baseline target.

If you want to hear Gillett unpack protein targets, meal timing, and satiety hormones, listen to the full episode on Youtube.

Why does sleep matter so much for hormone regulation?

If exercise and nutrition create the demand for adaptation, sleep is where much of that adaptation gets carried out. Gillett says sleep quality and sleep continuity both matter because important hormone pulses happen during longer, uninterrupted stretches of sleep.

Growth hormone is his first example. It is released in pulses, mostly during sleep, and plays a role in recovery and muscle regeneration. Testosterone is closely tied to sleep as well, because upstream signals such as gonadotropin releasing hormone, luteinizing hormone, and follicle stimulating hormone follow sleep linked patterns. When sleep becomes fragmented, those signals can become less effective.

That helps explain why Gillett keeps returning to sleep apnea and shift work. In his view, people with untreated sleep pathology often carry a cluster of issues that overlap: lower testosterone, lower sperm counts, more body fat, less lean body mass, and a weaker sense of recovery. WHOOP can add context here because Sleep, Recovery, HRV, and resting heart rate often show the downstream effect of disrupted sleep before a person fully connects the dots.

Holmes adds a useful performance lens. She notes that sleep quality has a strong relationship with HRV, especially REM sleep and slow wave sleep. Time in bed still matters, but the quality of that time changes how recovered someone feels and how prepared they are to handle stress and training the next day.

Gillett summarizes the mechanism directly:

“Growth hormone is a pulsatile secretion, mostly during sleep.”

What you should take away

• Sleep supports hormone release patterns tied to growth hormone, testosterone, and fertility.
• Fragmented sleep can interfere with those hormone pulses even when total sleep time looks acceptable.
• Sleep apnea and shift work can contribute to lower lean mass, higher body fat, and poorer recovery.
• WHOOP metrics such as Sleep, Recovery, HRV, and resting heart rate can help you spot patterns worth discussing with a clinician.

If you want to hear Gillett go deeper on growth hormone, sleep apnea, and recovery, listen to the full episode on Youtube.

How do stress, sunlight, and daily routine affect hormone health?

Sleep does not start when you get into bed, it starts with what you do during the day. Gillett's framework ties sunlight, routine, stress, purpose, and social environment together as the upstream inputs that shape sleep and hormone regulation.

His most practical sleep rule is the 10-3-2-1-0 approach. In his version, caffeine stops 10 hours before bed, alcohol stops 3 hours before bed, food and exercise stop 2 hours before bed, bright light and screens stop 1 hour before bed, and the snooze button stays at zero the next morning. The goal is to give the nervous system and circadian system a cleaner runway into sleep.

Morning light matters for the same reason. Gillett recommends getting sunlight early in the day, which helps cue the circadian rhythm that controls melatonin and cortisol timing. He also places sunlight inside a wider environmental category that includes heat and cold exposure. Cold exposure in the morning can fit well for some people, while heavy cold exposure too close to bedtime may interfere with sleep.

Stress is where his model gets more nuanced. Gillett draws a line between intentional stress and unintentional stress. Exercise, cold exposure, meditation practice, and sauna work are examples of stressors that people choose and prepare for. Traffic, work chaos, and family overload often land very differently because the body experiences less control. He compares it to the difference between loading a movement in the gym and getting pulled into the same movement unexpectedly in a car crash. The mechanics might resemble each other, but the physiological experience does not.

He also argues that a sense of purpose and a healthy social environment can change the whole system. If someone lacks direction, sleep, diet, and exercise habits often weaken as well. That is why Gillett keeps spirit, and now social health, inside the broader hormone conversation.

His rundown is compact and specific:

“I do like the 10-3-2-1-0 rule. So no caffeine within 10 hours, 3 hours, and then 2 hours for eating and exercise. And then 1 hour for bright white or blue light or screens, and then zero snooze in the morning.”

What you should take away

• Morning sunlight helps set the circadian signals that influence melatonin and cortisol timing.
• Intentional stressors such as training, cold exposure, and meditation can build stress tolerance when used well.
• The 10-3-2-1-0 rule gives a simple structure for protecting sleep quality.
• Purpose and social environment can influence hormone health indirectly by shaping daily habits.

Which supplements did Dr. Gillett highlight for hormone support?

Supplements sit below training, food, and sleep in Gillett's hierarchy, but he still sees value in a few of them when they match the person and the goal. Creatine is the standout because he connects it to cellular energy, exercise output, and hormone related performance.

Holmes shares a useful WHOOP data point to set up the discussion. During a 90 day period, more than 38,000 WHOOP members logged creatine in the WHOOP Journal. On days when members recorded taking creatine, average daily Strain was 12.3, which Holmes says was 12.2 percent higher than on days without a creatine entry. Gillett's explanation is that creatine acts as backup energy support for cells, which can make hard work feel more available.

He also notes a lab caveat. Creatine can raise creatinine, which may look concerning on routine blood work even when kidney function is fine. In cases where that question matters, he says cystatin C is a better marker of kidney filtration.

Beyond creatine, Gillett mentions vitamin D, especially in periods of lower sun exposure. Magnesium also makes his list, particularly forms that cross the blood-brain barrier, such as glycinate and threonate, because they may fit well into an evening routine. Melatonin gets a more careful treatment. He sees it as useful in jet lag and time zone shifts, but he does not frame high dose, routine melatonin as a universal answer.

Gillett's simplest description of creatine is also his most memorable:

“The way I explain creatine is it's a backup fuel tank for your energy system.”

What you should take away

• Creatine is the supplement Gillett discusses most directly for training capacity and cellular energy support.
• WHOOP Journal data in the episode showed higher average Strain on days when members logged creatine use.
• Cystatin C can be more informative than creatinine when someone taking creatine wants a clearer kidney function marker.
• Vitamin D, magnesium, and selective melatonin use can fit into a broader recovery plan when the use case is clear.

The bottom line

• Hormones act as signaling molecules that influence metabolism, sleep, heart rate, appetite, reproduction, and exercise adaptation.
• Resistance training helps protect lean body mass and bone density, which supports healthier metabolism and body composition over time.
• Zone 2 cardio and brief maximum effort intervals serve different purposes, and both can support hormone related fitness and recovery.
• Daily protein intake of at least 0.7 grams per pound of body weight is Gillett's baseline for most people, with higher targets during heavy training or older age.
• Sleep quality and sleep continuity support the release patterns of growth hormone and other reproductive hormones tied to recovery and body composition.
• Morning sunlight, a consistent pre-sleep routine, and intentional stress practices can improve the daily conditions that support hormone regulation.
• Creatine, vitamin D, magnesium, and selective melatonin use can support performance or sleep, but they sit below training, food, and sleep habits in importance.
• WHOOP metrics such as Sleep, Recovery, HRV, resting heart rate, Strain, and WHOOP Journal logs can help connect daily habits with changes in recovery and performance.

Frequently asked questions about things discussed in this episode

How does WHOOP help you spot when sleep might be affecting hormone health?

WHOOP helps you spot sleep related hormone patterns by tracking Sleep, Recovery, HRV, and resting heart rate together. A run of low Recovery, falling HRV, or higher resting heart rate after poor sleep can show that sleep quality is affecting the systems Gillett links to growth hormone and testosterone regulation.

What does WHOOP track that can reflect stress related changes in hormone balance?

WHOOP tracks HRV, resting heart rate, Sleep, and Recovery, which can reflect how the autonomic nervous system is responding to stress. Those signals do not diagnose a hormone condition, but they can show when stress load and recovery are moving in the wrong direction.

How does WHOOP help you connect training load to recovery when you are trying to support hormone health?

WHOOP helps connect training load to recovery by pairing Strain with next day Recovery and sleep data. That makes it easier to see whether your current mix of lifting, zone 2 work, and hard intervals is supporting adaptation or pushing you into a pattern of poor recovery.

What does WHOOP do for tracking creatine use?

WHOOP lets you log creatine in the WHOOP Journal so you can compare supplement use with Strain, sleep, and Recovery trends over time. In this episode, Holmes notes that WHOOP members showed higher average Strain on days when creatine was logged.

How does WHOOP help you test whether meal timing is affecting recovery?

WHOOP helps you test meal timing by combining journal entries with sleep and Recovery outcomes. Logging late meals, protein intake, alcohol, or caffeine can show whether those choices are lining up with better sleep quality or more overnight disruption.

What does WHOOP do for people tracking hormonal changes across the menstrual cycle?

WHOOP helps people track menstrual cycle related changes by pairing cycle logging with sleep, strain, and recovery trends. That makes it easier to see how different phases line up with changes in training tolerance, perceived effort, and nightly sleep quality.

Used consistently, WHOOP can show whether changes in sleep, strain, and logged habits are lining up with the steadier recovery patterns Gillett associates with better hormone health.