Should you try the 75 Hard challenge? Experts warn the risks may outweigh the benefits

By Lily Hautau, CNN

(CNN) — Five requirements. Seventy-five days. No breaks and no room for mistakes.

That’s the premise of 75 Hard, a challenge created by entrepreneur and author Andy Frisella and marketed as a “transformative mental toughness program” and “an ironman for your brain,” according to his website.

Chicago runner Sarah Lyons learned quickly how demanding the rules could be.

On paper, the daily checklist seems straightforward: Follow a structured diet with no alcohol, drink a gallon of water, read 10 pages of nonfiction, take a progress photo, and complete two 45-minute workouts, one outdoors, every day for 75 consecutive days.

In practice, the routine can take over your schedule and your life.

The challenge includes several healthy habits such as daily movement, reading and hydration, but experts say its rigid, all-or-nothing approach may undermine the long-term behavioral changes it promises.

For people drawn to 75 Hard, the goal shouldn’t be perfection but building habits you can keep when life inevitably gets messy, according to experts. Here’s what they say should be taken away from this challenge — and what could be left behind.

The ‘start over’ rule

One of the program’s defining features is its strictness: Miss one task and you restart the entire challenge, whether you’re on day 2 or day 74.

The website discourages modifications, saying that “compromise nerfs off the sharp edges of what could be an exceptional life.”

Before she started her first 75 Hard challenge, Lyons “felt stuck in a rut both physically and mentally.” Initially drawn to the structure of the challenge, she was looking for something to help rebuild discipline and momentum.

But that structure can backfire.

“Sustainable fitness isn’t about punishment or proving discipline through extremes — it’s about building habits that integrate into your lifestyle in a way that feels supportive and repeatable,” said CNN fitness contributor Dana Santas, a certified strength and conditioning specialist and mind-body coach in professional sports.

Forcing a restart after one deviation, Santas said, can reinforce a cycle of perceived failure rather than building durable behavior changes — especially when real life inevitably intervenes through travel, illness, family obligations, weather or simply an off day.

That mindset may also affect eating behaviors. It can contribute to binge eating, disordered eating patterns, negative body image and negative self-talk, warned Bethany Doerfler, senior clinical research dietitian at Northwestern Medicine Digestive Health Institute in Chicago.

People may also define “slip-ups” differently, she added, creating a potential gateway to unhealthy behaviors.

Lyons said the rigidity sometimes created stress in her own life, too. During her first attempt, she said there were many days when she delayed tasks until late in the evening, which added pressure rather than making her feel healthier.

With that strict framework in mind, experts say it’s worth separating the challenge’s healthier building blocks from the parts that may be risky or unsustainable.

One important note: Before beginning any new exercise program, consult your doctor. Stop immediately if you experience pain.

The diet: Flexible in theory, hard in practice

One element of the 75 Hard that does allow flexibility is the way people eat. Participants choose their own diet. That could mean Mediterranean, Paleo, cutting ultraprocessed foods or another structured approach.

But experts stress that any diet change works best when it’s designed for real life.

If you’re considering a structured eating plan, Doerfler points to the Mediterranean diet. It emphasizes fruits, vegetables, whole grains, legumes and nuts, uses plant-based fats, and limits ultraprocessed foods and desserts, she noted.

Lasting dietary change usually requires a lifestyle shift — and consistency matters more than intensity. “Patients often benefit from a routine strategy which reduces friction for lifestyle change,” she said.

Doerfler recommends setting aside one or two days each week to wash and cut produce for meal prep and snacks. She suggests having a plan for social settings so eating out feels manageable rather than stressful.

Lyons, the runner, said her diet evolved between her two attempts at the challenge. During her first round, she followed a strict whole-food, plant-based diet. During her second attempt, she focused on eliminating processed sugars, fast food and baked goods while still including meat and fish.

But she also noticed the rules changed how she navigated food socially. Lyons said she became cautious about eating out and often avoided restaurants because she felt anxious about potentially breaking the challenge.

Alcohol and water: One clear benefit and one major red flag

Food rules may be flexible in 75 Hard — but the drinking rules are not.

Participants must abstain from alcohol and drink 1 gallon of water each day.

Cutting back on alcohol can improve how you feel and lower your risk of cancer, heart disease, liver disease and memory problems to list a few, according to the US Centers for Disease Control and Prevention.

The water requirement, however, raises concerns among experts.

“I do not recommend drinking this much water,” Doerfler said. She noted 1 gallon is 16 cups of water. Experts recommend 9 cups of fluids for females and 12 ½ cups for males. Combined with a strict diet and increased exercise, there is a great risk of developing an electrolyte imbalance, particularly sodium, she said.

Symptoms of hyponatremia, or having abnormally low sodium levels in the blood, can include seizures, muscle cramping, nausea and vomiting according to the Cleveland Clinic.

Hydration needs vary widely depending on body size, activity level and climate, Santas said. While drinking enough water is important, rigid daily targets without guidance can disrupt sleep or contribute to electrolyte imbalances if large amounts of fluid are consumed quickly.

Lyons said the gallon rule often felt excessive. The frequent bathroom breaks often disrupted her routine and didn’t always feel necessary from a hydration standpoint.

Because the program requires two workouts a day, hydration and recovery can become even more important.

High-volume exercise with no recovery

Participants must complete two 45-minute workouts every day for 75 straight days — and one must be outdoors. This is where experts see some of the biggest physical and behavioral risks.

During her first attempt, Lyons quickly realized that using the outdoor workout primarily as a walk would be more feasible.

“Two high-intensity 45-minute workouts each day would not have been realistic for me long term ,” she said.

Santas pointed to the US Department of Health and Human Services Physical Activity Guidelines for Americans, which recommend 150 to 300 minutes per week of moderate-intensity activity (or 75 to 150 minutes of vigorous activity), with an emphasis on customization, progressive overload, recovery and sustainability.

“The 75 Hard structure far exceeds the recommendations and doesn’t provide any individualized guidance or programmed recovery,” Santas added.

The program’s claim that it works for everyone “regardless of physical fitness” may not hold up in practice, Santas said. Professional athletes or people with highly flexible schedules might manage it, but for many people balancing work and family, the structure can be unrealistic.

Even for those who complete it, Santas warned of overuse injuries, excessive fatigue and burnout due to unclear intensity guidance and zero recovery days.

Lyons experienced that challenge firsthand during her second attempt, which overlapped with training for the Boston Marathon. Long marathon runs can last 2 to 3 ½ hours and because the challenge prohibits combining workouts, she often had to complete a long training run plus an additional 45-minute workout.

On some days, this resulted in four or more hours of exercise.

It was “physically and mentally exhausting and ultimately unsustainable,” she said. In hindsight, she would not recommend pairing 75 Hard with marathon training. She found herself avoiding the gym because she needed physical and mental recovery, she added.

Lyons also questioned the rigidity of the outdoor-workout requirement. During her 2025 attempt, she was living in Chicago during winter, when temperatures occasionally dropped below zero. Exercising outdoors in extreme conditions felt unsafe and impractical, she said, and while she still completed two workouts daily, she chose to prioritize safety and consistency over strict adherence to that specific rule.

What habit science suggests instead

If the extreme discipline of Hard 75 isn’t the best way to build lasting habits, what does science-based research show?

“Habits are behaviors that we enact without deliberation,” said Dr.
Katy Milkman, James G. Dinan Endowed Professor at Wharton School of the University of Pennsylvania.

Imagine everyday routines like shampooing your hair or making coffee in the morning she said.

Habits are formed through repetition. The more often we repeat a behavior, the more likely it is to become habitual and go on autopilot, added Milkman, the author of “How To Change : The Science of Getting From Where You Are to Where You Want to Be.”

“They’re formed through positive associations and rewards,” she said. Picture your caffeine buzz after drinking a coffee or getting paid after you complete your work, these habits are often triggered by a common cue like a location, time or even smell.

It takes a set number of days to form a habit, Milkman said, but she noted that more complex habits typically take longer to become automatic.

“The more friction you put between someone and execution of a habit the worse it is in terms of habit formation,” she said. “If you want to break a habit, you make it really hard to do.”

If someone is already regularly exercising, reading daily and staying well-hydrated, Milkman said, 75 Hard may be more doable. But for someone starting from scratch, she said the time and logistical burden of completing every requirement every day may be the biggest obstacle.

Lyons said one part of the challenge that did help her build a lasting routine was the daily reading component.

She said she genuinely enjoyed that requirement because she has many books she wants to read but often struggles to consistently set aside time for it. Across both attempts at the challenge, she finished four books each time, she said, and the structure helped rebuild her habit.

Keep the good, lose the rigidity

If you’ve heard of 75 Hard, you may also know about 75 Medium or 75 Soft, which include flexibility and customization for things like rest days or hydration goals and can be adjusted to meet people where they are.

That adaptability is often key to long-term behavioral change, experts say. There is no one-size-fits-all approach.

Lyons said she doesn’t believe 75 Hard is inherently negative, and she thinks it can work for people who are highly motivated by strict structure and intensity. But she believes it may be overwhelming for beginners or anyone starting from a low baseline of fitness — and she doesn’t support its extreme approach.

In her experience, sustainable consistency is built through adaptability and learning to recover from setbacks rather than viewing them as failures.

“There are positive elements embedded in the challenge — encouraging movement, outdoor time, reading and hydration — but I would advocate for a more structured, individualized and recovery-aware approach that aligns with established exercise science,” Santas said.

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