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Today’s Health Upgrade
Do vacations sap your muscle & strength?
The 3 variables that make (or break) your sleep
Why you can’t stop eating sweets (even when full)
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Fitness
What Happens To Strength And Muscle On Vacation?
Consistency is the key to building muscle and strength. But what happens when you can’t train as often? Do you lose all your progress — or is there a smarter way to maintain it?
New research suggests you can still keep your muscle and strength even when exercising less often — if you’ve already built a solid foundation.
For 12 weeks, participants followed a resistance and aerobic training program. Then, they were split into groups for another 12 weeks where training was reduced. Some trained just once per week, other took off 14 days, and a third group stopped exercising completely.
The study focused on changes in muscle strength, muscle thickness (size), and performance measures like VO₂ max. After the initial 12 weeks of training, everyone saw significant improvements in all markers — no surprise there.
But here’s where it gets interesting: those who cut their training frequency in half (from twice per week to once per week) maintained nearly all of their muscle strength and size. Even at one workout per week, the participants maintained 95 percent of their lower body strength and muscle mass.
Those who reduced it to one workout every two weeks lost a meaningful amount of muscle, but maintained most of their strength (but with some losses).
Those who stopped training, as you might imagine, saw decreases in strength, muscle, and aerobic capacity.
Researchers believe the key lies in something called the “retraining effect.” Once you’ve built muscle and neural adaptations, your body becomes more efficient at maintaining them, even with reduced stimulus. It’s like giving your body just enough to remind it what it’s capable of.
This is not encouragement to intentionally cut back on training. But it is a reminder that if you find yourself in a chaotic season of life — or on vacation and not able to train as you normally do — you don’t have to panic or assume all your hard work will vanish. As little as one high-quality session per week may be enough to hold onto your progress — especially if you focus on compound lifts and maintain intensity.
In general, anything more than 14 days off will start to lead to decline, and your aerobic endurance might drop off quicker than your strength.
The real lesson is for those to breaks to be few and far between and to focus on a consistent routine that allows you to exercise at least two to three times per week. So, don’t stress if life gets hectic. Even reduced training is better than none.
Together with Eight Sleep
The 3 Factors That Make or Break Your Sleep
If you want better sleep, forget the gimmicks—science says a few key habits can make all the difference.
A thorough study from the Human Phenotype Project found that sleep quality is deeply connected to your lifestyle, your microbiome, and the temperature of your bedroom.
Researchers analyzed data from more than 6,000 individuals, looking at 448 diverse sleep characteristics across 16 body systems to uncover which factors had the biggest impact on sleep duration and quality.
Their findings revealed three key insights that could help you fall asleep faster, stay asleep longer, and wake up feeling truly rested.
The lifestyle variables include many of the usual suspects, such as drinking alcohol, a lack of exercise, too much stress, eating right before sleep, and spending time on devices. Cutting back on any of those can help improve your sleep.
But there were less-obvious changes too.
Your microbiome—the trillions of bacteria in your gut—doesn’t just affect digestion; it plays a major role in sleep regulation. The study found that people with higher microbial diversity had better sleep efficiency and fewer nighttime awakenings and less sleepiness. The scientists believe it’s because gut bacteria help regulate serotonin and melatonin, two hormones that influence sleep.
On the flip side, poor gut health—often caused by too much ultra-processed foods, antibiotics, or low fiber intake—was linked to sleep disturbances and even insomnia.
If you want to improve your sleep, you don’t even need supplements. You can feed your gut the right way by eating more fiber (fruits, vegetables, and whole grains), consuming fermented foods like yogurt, kefir, or kimchi, and avoiding excessive processed foods and sugar.
These diet changes have an additional benefit of keeping you leaner, which also helps because the study found a strong link between body fat and sleep apnea.
The study also found that if you want to feel more rested, process information better, and help protect your brain against degenerative disorders like dementia, your bedroom temperature can make or break your sleep quality.
The study found that people who slept in cooler environments (around 65°F or 18°C) experienced deeper sleep and fewer awakenings.
A cooler room mimics the natural drop in body temperature that occurs before sleep, helping you fall asleep faster and stay in restorative sleep longer. On the other hand, warmer bed temperatures (above 70°F or 21°C) were associated with more restless sleep, difficulty falling asleep, and increased wake-ups throughout the night.
If you struggle with sleep, try lowering your bedroom temperature, using breathable bedding, and even taking a warm shower before bed (which helps cool your body down).
Or, you can purchase the Eight Sleep Pod 4, a scientifically proven way to improve your rest. Research suggests that the Eight Sleep can instantly improve your sleep within one month.
In the study, those using the sleep pod fell asleep faster, slept longer, had fewer sleep disturbances, and had more energy the next day. Specifically, they increased their deep and REM sleep, improved cardiovascular recovery, and reported feeling calmer and more comfortable.
The Eight Sleep Pod not only allows you to control your temperature, but it recognizes your sleep patterns and automatically adjusts the temperature to help promote deeper and more restful sleep, and makes it easier to wake up without feeling groggy.
As members of the positive corner of the internet, use the code “PUMPCLUB” to save up to $350 OFF the new Pod 4 by Eight Sleep, including a risk-free 30-day trial. Eight Sleep currently ships within the United States, Canada, the United Kingdom, Australia, and select countries in the EU.
Nutrition
Why You Can’t Stop Eating Sweets (Even When You’re Full)
You know that moment after you finish a meal and you have room for one bite of dessert — but you somehow become ravenous once the treat hits your lips? Your hunger might have nothing to do with willpower. It’s your brain chemistry at work.
New research suggests that dopamine can override your body’s natural “I’m full” signal—making it easier to eat for pleasure, not hunger.
Researchers explored how the brain balances eating for your body’s energy needs (homeostatic eating) with eating for pleasure (hedonic eating). They focused on two opposing forces: dopamine neurons that drive the desire to eat and neurons that carry GLP-1R (glucagon-like peptide-1 receptors), which typically signal fullness and reduce food intake.
You might recognize GLP-1 as the hormone that’s activated in the new weight loss drugs like Ozempic and Wegovy. These new medications are so effective because they regulate appetite and blood sugar beyond what you can normally activate through diet or exercise.
When you're enjoying food, your dopamine circuit ramps up and suppresses your satiety signals. So, even if you're full, your brain keeps saying, “Keep going, this is delicious.”
The scientists studied this pathways in mice, and when dopamine neurons were blocked, the mice consumed less high-fat, high-sugar food—even though the same food was available.
In other words, a surge in dopamine — which you can get from your favorite dessert — dampen the response of GLP-1R neurons, which normally suppress appetite. So the drive to eat dessert — and then the moment when the deliciousness hits — can result in you eating far more than you want.
So what does this mean for your everyday health?
It confirms what many of us feel: cravings and pleasure-driven eating aren’t just about discipline. They’re the result of brain circuits that actively oppose your body’s satiety system.
And yet, mind-control or not, it’s up to you to take control of your hunger. To work with your biology, not against it:
Focus on foods that activate fullness signals (like those high in protein and fiber).
Eat slowly (take at least 20 minutes per meal) to give satiety hormones time to work before dopamine takes over.
If you know dessert is a problem either pass on it or do so with such a small serving size that you’re not a dopamine victim.
And if you find yourself eating when you're not hungry, know that it’s not about weakness—it’s your brain's reward system doing exactly what it’s designed to do.
Understanding how dopamine and hunger systems compete can help you make better decisions when cravings hit—and reduce the guilt that often follows.
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Publisher: Arnold Schwarzenegger
Editors-in-chief: Adam Bornstein and Daniel Ketchell
