clenbuterol benefits

Clenbuterol for Bodybuilding (7 Benefits)

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Clenbuterol, also known as clen, was originally formulated for the treatment of breathing disorders that are related to recurrent airway obstruction (RAO) and inflammatory airway diseases (IAD). However, a number of scientific studies confirmed clen to be an effective fat-burning and muscle-sparing supplement.

Consequently, clenbuterol has been a favorite supplement among bodybuilders for over 25 years, as well as fitness professionals, athletes, models, celebrities; and everyday gym-goers who simply want to lose fat.

Clenbuterol’s usually taken in pill form, however it’s also available via injection, syrup or inhalation.

If you’re interested in taking clenbuterol, it’s important to know about it’s benefits and side effects. Read on to find out how it can help you with your bodybuilding needs.

clenbuterol benefits

Clenbuterol Benefits

1. Increases Metabolism/Burns Fat

Clen’s ability to burn fat is what makes it famous, but how does it work exactly?

Clenbuterol’s proven to boost the metabolic rate of the body in a process commonly known as thermogenesis, which plays a major role in combating excess weight. Thermogenesis is the process where your body’s temperature increases. With your body desperately trying to keep a homeostasis, it tries to cool itself back down to normal.

As a result of this ‘constant cooling’, the body burns additional calories and thus a users BMR increases. The longer you take clen for, the more spiked your metabolism will be.

Clenbuterol also promotes lipolysis, the process where your body draws on stored fat as fuel and helps to give you more energy.

By increasing the heat and energy produced in the mitochondria cells and stimulating the central nervous system, you’ll burn more calories and fat in a shorter period of time. Clenbuterol’s fat loss benefits are pretty dramatic in the first 2 weeks of use. Clenbuterol’s also effective at reducing stubborn fat, particularly in the visceral and abdominal areas; which is often the hardest places to lose fat from.

2. Increases Blood Flow and Oxygenation

Initially, clen was used to treat asthma patients because it improves aerobic capacity and boosts oxygenation, as well as transportation of blood in the body. Bodybuilders can also experience a whole host of benefits from having increased blood flow and oxygenation, without necessarily being an asthma patient.

With more oxygen flow, you’ll increase your body’s muscular endurance. This is very important when you’re training in the gym, as it’ll help you to train longer. It will also speed up your recovery levels in-between workouts, enabling you to increase your training frequency.

Clen will also reduce any muscle soreness/pain that you can experience from a tough workout. Delayed onset muscle soreness is a tough reality for many dedicated weight lifters; however this effect is unlikely to happen on clenbuterol due to its positive effect on muscle recovery.

Thus it comes as no surprise that clenbuterol is talked about highly by thousands of happy users.

3. May Build Muscle (Small Amount)

Human studies on Clenbuterol show that the supplement has a positive effect on skeletal muscle. Clen has long-acting systemic beta 2-agonists, which can increase the size of skeletal muscle fiber and accelerate the creation of new muscle tissue generation.

Although clen isn’t as anabolic as steroids, it’s shown to be effective at getting rid of the stubborn fat whilst simultaneously gaining lean muscle mass.

Animals studies also support clenbuterol increasing lean body mass (seen in rats, mice and horses). It’s believed that clenbuterol’s anabolic properties are the result of it increasing protein synthesis levels.

Some bodybuilders don’t notice much, in regards to muscle gains on clenbuterol, however other users swear that it helps them add lean mass. Thus, more research is needed before clen’s classed as a muscle-building drug.

So, it may not be wise to use clenbuterol during a bulking phase as its muscle-building effects are generally only mild. However, it does have muscle preservation effects, making it very beneficial to use during a cutting cycle.

Preserving muscle mass, whilst losing fat, is one of the most difficult goals for a bodybuilder to achieve.

When you preserve your muscle tissue, not only are you keeping your hard-earned muscle in-tact; but your metabolism will also remain elevated, enabling further weight loss.

4. Increases Energy Levels 

goku showing high energy levels

Clenbuterol stimulates the central nervous system and thus increases your heart rate and adrenaline levels. As a result, users often report having higher energy levels throughout the day; and increased motivation to achieve their goals.

This adrenaline-like effect also increases the intensity of users’ workouts, helping them to lift heavier weights, perform more reps; or simply workout for longer periods of time. This can indirectly help a user increase strength, build muscle; or burn more fat.

Higher adrenaline levels can result in a user feeling somewhat ‘hyper’. However, if you consume stimulants on a daily basis such as caffeine, in the form of cups of tea or coffee; this effect isn’t likely to be too extreme.

5. Appetite suppression

Even though clen is typically identified as a metabolism-stimulator for weight loss, one of clenbuterol’s little-known benefits is appetite suppression. Research confirms the supplement works by stimulating a very sensitive beta 2-adrenergic system, which has a profound effect on the feeding behaviors in humans. This means you’re not likely to feel hungry throughout the day and it may stop all cravings.

This is very beneficial if you struggle to eat in a calorie deficit. Consuming less calories than your body expends on a daily basis is crucial for fat loss; thus by taking clenbuterol, you’ll naturally feel less desire to eat larger portions.

6. No Testosterone Suppression

gorilla with high testosterone

Clenbuterol isn’t a steroid, however it’s often mistaken as a cutting steroid; due to its powerful fat-burning effects. The main difference between cutting steroids and clen is their effect on testosterone levels.

Cutting steroids will shut down test levels, meaning that it can take several months after a cycle finishes for natural testosterone production to return to pre-cycle levels.

However, clenbuterol has no obvious effect on testosterone levels, thus when you finish your cycle, your testosterone levels will stay in tact.

Testosterone also helps to burn fat, so keeping this hormone elevated is key to long-term fat loss.

7. Diuretic-Effect

Clenbuterol does have mild diuretic effects, meaning you’ll lose water weight, as well as fat mass on this drug.

This is due to increased sweating, as a result of thermogenesis heating up the body. Consequently, users sometimes report urinating more than usual when they start taking clen.

Losing water weight can make a bodybuilder look more aesthetic, due to it increasing muscle definition and reducing bloat. This makes it a popular fat burner in the summer, when people are trying to look as tight and toned as possible.

Clenbuterol Results

sylvester stallone before after fat loss
Typical clenbuterol transformation

Weight loss can be dramatic whilst using clenbuterol, especially if the user’s eating in a calorie deficit and working out regularly and intensely throughout a cycle.

How much fat you’ll lose will depend on how you respond to the drug, your genetics, diet, workouts, dose and how long you cycle for. However, on average, users can expect to lose 8lbs from 4 weeks on clen.

If you combine clenbuterol with thyroid hormones such as Cytomel, you can increase thermogenic activity even more than a clen-only cycle.

Also stacking clenbuterol with cutting steroids, or human growth hormone, will further accelerate fat burning (and muscle retention).

Here’s a before and after picture of Sylvester Stallone. We believe he’s likely to have used clenbuterol for this transformation. He has flushed skin, a visual sign of thermogenesis in action.

Is Clen Safe?

Clenbuterol is not currently approved for human-use. Thus it’s deemed unsafe by the FDA. However, doctors do prescribe clenbuterol regularly to those suffering from asthma.

Both of these statements should indicate to users that there are dangers, however if clenbuterol’s used sensibly (especially under medical supervision) for a short period of time, side effects are unlikely to be severe.

Here’s some adverse effects that can happen on clen:

  • Increase in blood pressure
  • Insomnia
  • Increased sweating
  • Possible anxiety
  • Jitters (shaky hands)

Side Effects

An increase in blood pressure is probable due to clenbuterol constricting blood vessels, making it more difficult for blood to flow to and from the heart. Thus if you have a history of heart disease or have existing high blood pressure, you should stay away from clenbuterol. However, in most users, blood pressure will simply rise a little and then drop back down once they stop using the drug.

Because clenbuterol increases adrenaline output, this can cause a user to become excessively stimulated in the evening, leading to insomnia. To prevent this side effect, the user can take pills earlier in the day. However, make sure there’s a gap of at least a few hours inbetween each pill to minimize adverse effects (you don’t want to take a high dose in a short space of time).

woman sweating from exercise

Increased sweating is a common reality among clen-users, especially towards the end of their cycle. This is a good sign, as it’s proof of thermogenesis (increased body heat), which is key for fat loss.

Be sure to drink plenty of water on clenbuterol to reduce the risks of dehydration.

Anxiety is a possibility for anyone who takes clen or stimulants in general, due to them initially increasing dopamine levels (the feel good hormone), but later reducing serotonin levels (the neurotransmitter essential for mental well-being).

Like alcohol withdrawal can cause the shakes, so can clenbuterol (particularly in the hands). The only way to prevent this is to keep your dose low-to-moderate.

How to Take It?

Clenbuterol usually comes in 20mcg tablets. Bodybuilders will typically take 1-2 tablets a day (depending on their tolerance), and increase their dose by 0.5-1 tablet every 3 days

In terms of cycle duration, less is certainly more on clenbuterol. This is because after a certain period of time, clen will stop being effective for fat loss, because of receptor down-regulation.

Clen usually starts to wear off after 4-6 weeks. Thus it’s optimal to keep cycles short, otherwise you’ll be wasting your money.

You can tell if clenbuterol’s effects are wearing off by monitoring your body temperature. If your temperature begins to drop, this is a sign of clen’s thermogenic effects decreasing.

Experienced bodybuilders who’ve built up a tolerance to the drug, can adopt an aggressive dose to burn more fat (some do this before a competition) and take as much as 120-160mcg a day (6-8 tablets).

High doses will cause more side effects, especially in terms of strain on the heart and elevated blood pressure.

With higher doses, the cycles should become shorter. When taking a higher dose, 2 weeks on and 2 weeks off is a common protocol. Also short cycles will prevent your body from getting used to the drug, and thus you can expect good results with each new cycle.

Beginners should also be cautious when taking clen for the first time, starting on a smaller dose (20-40mcg) and increasing the dose slowly as their body adapts. If you’re experiencing side effects, do NOT up your dose; as this will only exacerbate the effects.


Clenbuterol, when used correctly, can be a very effective fat burner. In regards to the side effects, it’d be best to to get a check-up by your doctor to make sure you’re in good health; and then to be monitored throughout your cycle to make sure your blood pressure is within a normal range.

Also, for maximum results, users may need to make lifestyle changes; such as eating healthy, doing regular cardio and getting adequate rest.

It’s very important to follow the dosage instructions when taking clenbuterol, as it’s a powerful compound and shouldn’t be taken lightly.

In conclusion, when you add clenbuterol to your workout regime – you’ll enhance fat loss and increase the chances of achieving a leaner body. Muscle gains shouldn’t be expected, however clen may help to prevent muscle loss when eating in a calorie deficit.

clenbutrol supplement advert








Llewellyn, William (2011), Anabolics. Jupiter, FL: Molecular Nutrition. pp. 899-904.

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The author

Ernst Peibst
Ernst Peibst has spent over 3,000 hours researching anabolic steroids and PED’s. He’s also dedicated the last 7 years educating people about their effects, with hundreds of thousands of people reading his articles. He’s studied countless science papers, read several expert books and has consulted some of the finest doctors in the world – on the topic of steroids.

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