When you start working out regularly, just one HIIT, lifting, or yoga class can feel transformative. But objectively, it may take a bit of time for your body stats (heart rate, VO2 max, weight, etc.) from your sweat sessions to shift on your Apple Watch. So, how long does it actually take to see results from working out?

The reality is, seeing changes to your physical and mental health from working out is both a short- and long-term game. The gains that come with increasing your muscle definition, losing weight, or shaving minutes off a half-marathon P.R. won’t happen overnight, experts say.

Meet the experts: Danyele Wilson, CPT, is a trainer for the app EvolveYou. Jason Machowsky, RD, CSCS, is a board-certified sports dietitian and registered clinical exercise physiologist. Brooke Taylor, CPT, is a a NASM- and ACE-certified personal trainer and owner of Taylored Fitness NY LTD. N'Namdi Nelson, CSCS, is an exercise physiologist at the NYU Langone Sports Performance Center.

Exactly how long it takes to see results from working out varies widely, says Danyele Wilson, CPT, trainer for the app EvolveYou. Those noticeable physical changes from exercise (be it increased muscle mass, fat loss, or a lower resting heart rate) depends on the person and their baseline level of fitness. "My [clients] generally see initial changes within four to six weeks, and actual results within eight to 12 weeks," Wilson explains.

And, no two people have identical goals or workout programs to reach them, meaning that the general timeline to see results of any kind (eight to 12 weeks) is pretty malleable.

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Here, fitness experts delve into how long it takes to see results in aerobic capacity, weight loss, muscle definition, mental health, and more—and what it actually takes to get there.

How Long It Takes To See Improvements In Aerobic Capacity

Upping your cardiovascular endurance and shaving minutes off your racing time doesn’t just result in a serious self-confidence boost—you’re likely to gain a trove of other health benefits, too. In fact, marathon training can help to decrease stiffness in your arteries and combat high blood pressure, a recent study in the Journal of the American College of Cardiology found.

Of course, scoring a new PR and lowering your heart rate a few beats per minute are two very different goals—with varying timelines. If your aim is the latter—to generally boost your cardiovascular health—eight to 12 weeks is a fairly solid period to do so, says New York City-based Brooke Taylor, a NASM- and ACE-certified personal trainer and owner of Taylored Fitness NY LTD.

“This involves a minimum of 30 minutes of moderate-intensity cardiovascular exercise three times per week,” Taylor explains, noting that several other factors—from sleep patterns to even your menstrual cycle—can play a role in your resting heart rate.

If you're a beginner, you'd ideally want the exercise to get you to 30 to 40 percent of your heart rate reserve. (To calculate your heart heart rate reserve, subtract your age from 220, then subtract your resting heart rate. Then, take 40-60 percent of that number and add your resting heart rate back in, and you'll get your moderate heart rate intensity.)

A supercharged style of aerobic exercise like interval training and high-intensity interval training (HIIT) can improve your resting heart rate, possibly even faster, Wilson also points out. “An athlete can typically start to lower their heart rate within a couple of weeks of training,” she explains. “Evidence suggests that interval training is the superior method to do so.”

In general, it takes about eight to 12 weeks to boost your cardiovascular health and endurance, experts say.

One study published in the Journal of Translational Medicine found that HIIT in particular can have a greater impact on reducing resting heart rate than both MIIT (moderate-intensity interval training) and MICT (moderate-intensity continuous training, like jogging).

As for an improvement in your speed and endurance, Wilson and Machowsky explain that it depends on the individual, and it's largely based on your training history and current fitness level. For instance, endurance-wise, your aerobic capacity might feel better in four to six weeks, but it'll take longer for there to be objective improvements.

“If you are currently inactive, you can see improvements to your VO2 max capacity within four to six weeks,” Wilson says. “Depending on the training program, a beginner can be half marathon-ready in roughly 12 to 20 weeks.” FYI: VO2 max is basically the maximum amount of oxygen your body can consume and deliver to your organs and muscles, according to the American Council on Exercise. The higher your capacity, the longer, and stronger, you’ll be able to engage in cardiovascular exercise.

How Long It Takes To Lose Weight (And Keep It Off)

First thing’s first: The decision to lose weight is a highly personal one. And not everyone is at the same starting point when it comes to shedding pounds. If you have a history of being overweight (or a family member who does), have been diagnosed with a hormonal disorder, are experiencing a mental health issue (like depression or anxiety), or are on certain medications, it might be more difficult for you to lose weight.

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Extraneous factors preventing weight loss aside, a calorie deficit still remains king for weight loss, notes Taylor. Basically, in order to lose one to two pounds per week (which Taylor notes is the safe, sustainable rate at which you can effectively shed pounds), you need to create a weekly 2,000 calorie deficit, she says.

If you're trying to measure weight loss through waist circumference or body fat percentages, generally wait eight to 12 weeks to notice a difference, or even upwards of 16 weeks, Machowsky says. (If you're following a specific weight loss program, it could take less time to see differences, he says.)

As for when that weekly deficit will result in noticeable changes you—and others—can see? While it depends on a number of factors (10 pounds might look different on your average 5’2” woman as opposed to a 6’3” competitive athlete), one 2015 study from Social Psychological and Personality Science found that a 2.93 change in BMI (or body mass index) was what it took to make weight loss (in your face, at least) apparent to others.

And while *technically* you could create that calorie deficit through exercise alone, think about it: Although it could take you minutes to consume 300 calories, burning that same amount could take upwards of an hour!

That being said, if there’s one exercise that can considerably boost a weight-loss effort, it’s strength training. A review of studies in the journal Metabolism found that the best way to boost your basal metabolic rate (BMR), or how many calories you’re able to burn at rest, is to have more muscle mass. And the magic ingredient behind increased muscle mass? You guessed it: hitting up the weight room.

This 30-Minute Workout Is The Perfect Balance Of Strength And Cardio
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HIIT might also contribute to a longer-lasting calorie burn, according to a 2017 study from the European Journal of Applied Physiology. When compared to steady-state, moderate-intensity cardiovascular training, participants in the study who engaged in HIIT continued burning calories long after their training was over. (The study notes that, while there’s a modest calorie burn after a moderate-intensity workout, it’s not nearly as much as HIIT.)

Of course, to reiterate (over and over), weight loss is a multifaceted, complicated journey. Taylor believes that the combination of that calorie deficit, strength training, and cardiovascular training will result in the speediest route to get there. “When a client is onboard [with those three changes] and is willing to adapt, big changes can happen within three to six months,” she says. “Again, however, it depends on how well the client adheres to the program.”

How Long It Takes To See Muscle Gains And Strength Increase

Unlike improving your cardiovascular health or losing weight, you might see increased muscle gains from a strength training program after a single session, research has shown. That’s due to a phenomenon called “muscle pump,” which is just a casual term for the increased blood, oxygen, and lactic acid that’s being moved to your muscles during a super-intense lifting session. (Granted, it’s only a temporary movement of fluids, but hey, it’s something!)

Machowsky adds that strength gains can initially happen within four to six weeks if you're new to lifting because of neuromuscular adaptation—a.k.a., your body is becoming "more efficient using the existing muscle to move the weight," he says. It's less about an increase in muscle mass and more about the efficiency of the muscle, he adds.

Consider that initial boost in your muscle size a preview of gains to come—which occur roughly six to eight weeks into a strength training program if you’re a beginner, and eight to 12 weeks if you’re more advanced, says Wilson. However, she notes, “this is going to look different for everyone because there are a lot of factors that play into muscle hypertrophy.”

But there's another factor at play here. "Muscle definition is usually tied to things like body composition," Machowsky explains. "Definition has to do more with your body composition than the strength itself." I.e., you can be stronger without looking "leaner," if you're not following a calorie deficit, so you're still the same weight.

If you're a beginner, expect to see muscle gains roughly six to eight weeks into a strength training program.

One of the biggest factors in expediting your gains, says Wilson? Protein. “Your daily protein intake plays an important role in muscle growth,” she explains. She recommends aiming to consume 0.5 to 0.8 grams of protein per pound of body weight per day if you really want to make a dent in your muscles. (So, a 150-pound woman would need to consume at least 75 grams of protein per day.)

As for the training pattern to get you to that point, Wilson says that three to five strength training sessions per week, using six to 12 repetitions for three to five sets at 75 to 85 percent of your one-rep maximum (1RM), is your best bet. If you’re not sure what your 1RM is, choose a weight that, on the final rep, feels super-challenging (but not impossible). Oh, and keep your rest in-between sets to no longer than 60 seconds, adds Wilson.

But what if your goal isn’t to have bulging biceps—but to lift the heaviest possible weight you can? Once again, food comes into play big time, says Wilson. “Think of your nutrition as your fuel,” she explains. “If you’re not eating enough calories to sufficiently fuel your body, you won’t have the energy required to meet the maximal demands of strength training. If you want to improve strength, a calorie surplus is generally recommended.” (What this means: You’d generally need to be consuming more calories than you’re burning.)

As for the type of training that will get you to that point, Wilson recommends two to four sessions of strength training per week containing four to six sets of one to five reps at 85 to 100 percent of your 1RM, and three to five minutes of rest in-between each set. Resistance training helps you form lean mass, which "helps kind of tell your body to maintain its muscle as you lose weight," Machowsky adds.

How Long It Takes To Lower Blood Pressure

This health markers may not sound as sexy as building muscle or knocking off a race PR, but it is oh so important to overall wellbeing. With a consistent workout routine (think four to six cardio workouts a week), you can see a decrease in blood pressure and resting heart rate in as little as two to three weeks, according to N'Namdi Nelson, CSCS, an exercise physiologist at the NYU Langone Sports Performance Center.

In general, you can expect a decrease in blood pressure as quickly as two to three weeks, experts say.

Here's how it works: As you increase your cardio capacity, you're exerting yourself, so your heart rate increases to pump blood around your bod faster. For example, when someone who's sedentary joins a HIIT class, their heart rate will shoot up very fast, maybe even to their max, since they have no aerobic base. Their cardiac muscles aren't used to that active movement.

However, as that same person works out more, their blood pressure will decrease, and so will their resting heart rate as their bod adjusts. Generally, you want to aim for a blood pressure reading of 120 over 80 at a doc appointment.

Resting heart rate naturally follows. "The lower the resting heart rate, the better," says Nelson. Studies have shown that a low resting heart rate is linked with longevity, Nelson explains. A healthy resting heart rate to aim for is between 40 to 60. That's a sign of solid cardio health. If your heart rate is a bit higher, that's okay, However, a resting heart rate in the 80s or 90s is a sign you need more physical activity in your routine to bring it down, she adds.

Keep in mind the two-to-three weeks timeline is on the speedy side. It may take four to 12 weeks to see the blood pressure and resting heart rate numbers drop, Machowsky adds. "You would need consistent activity for three months to feel like you can move the needle in an objective way," he says. (Think 20-30 minute sessions and five days a week of moderate aerobic activity or three days of higher intensity activity weekly, according to ACSM guidelines.)

Like the other workout goals above, the time it takes to change blood pressure varies for each individual and how quickly someone responds to exercise, says Machowsky.

How Long It Takes To Impact Mental Health

Brace yourselves, as little as five minutes of moderate exercise can produce a mood boost, according to the American Psychological Association. That's right, five minutes to turn that frown upside down!

It goes deeper with more time (four to six weeks), according to Nelson. "Research is very solid, showing that it is very helpful with helping fight depression and improving mood, and things like anxiety," Machowsky says. It also helps you become more confident when it comes to aesthetic ~gains~, Nelson adds.

As little as five minutes of moderate exercise can produce a mood boost.

"Exercise releases endorphins and dopamine, both of which are associated with improved mood," says WH advisor Chloe Carmichael, PhD, a New York–based clinical psychologist. "The increase of feel-good chemicals in the question above improve the mood, which can mitigate anxiety and depression."

Plus, when you commit to an exercise routine, it improves your sense of self-efficacy, or the sense that you can do what you say you do, accroding to Carmichael. These thoughts reinforce positivity, countering negative or depressive thoughts. Also, "one of the hallmark features of depression is a sense of helplessness," so when you work out and increase these self-efficacy feelings you can potentially mitigate depression, Carmichael adds.

Exercise also eases feelings of anxiety because it "boosts our belief that we can handle challenges, she adds. Plus, it's a healthy outlet for stress.

Headshot of Julia Sullivan, CPT
Julia Sullivan, CPT
Julia Sullivan, CPT, is a New York City-based writer, indoor rowing instructor, outdoor enthusiast, newbie powerlifter, and devoted cat mother. Her work has been published in Women’s Health, SELF, Health, Huffington Post, and more. She holds a B.A. in journalism and gender studies from Arizona State University and a personal training certificate from the American Council on Exercise. When she’s not covering the latest health and wellness trends, you can find her hitting the hiking trails, working toward her deadlift goal of 400 pounds, and forcefully hugging her cat, Jeeves, against his will.
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Addison Aloian (she/her) is an editorial assistant at Women’s Health. When she’s not writing about all things pop culture, health, beauty, and fashion, she loves hitting leg day at the gym, shopping at Trader Joe’s, and watching whichever hockey game is on TV. Her work has also appeared in Allure, StyleCaster, L’Officiel USA, V Magazine, and Modern Luxury Media.