¿Do Fat Burners Really Work?

A les La botiga de nutrició, we understand the concerns many athletes and fitness enthusiasts have about fat burners. These supplements claim to speed up weight loss and improve body composition. But do they really deliver what they promise, or are they just an overpriced investment?

What Are Fat Burners and How Do They Work?

Fat burners are supplements designed to support fat loss through various mechanisms. They don’t magically melt fat, but they can influence:

Main Mechanisms of Action

Boosting metabolism
Increases calorie expenditure at rest or during activity (especially thermogenic compounds).
Reducing appetite
Some ingredients help curb hunger, making it easier to maintain a sustained calorie deficit.
Partially blocking fat or carbohydrate absorption
Limits the impact of certain macronutrients in the diet.
Increasing energy and mental focus
Improves performance in workouts and helps with adherence to your plan.

Carnitina 3000 Llimona

Carnitina 3000 Apple NOU

Xtra L-Carnitina 20 Viales

Types of Fat Burners: Not All Work the Same

There are different categories of fat burners. Knowing them will help you choose the one that best fits your needs and tolerance.

Thermogenics

These are the most popular. They contain stimulants like caffeine, green tea extract, synephrine, or guarana, which raise body temperature and speed up metabolism. This helps increase calorie expenditure, even at rest.

Benefits:

Boost in energy
Improved performance
Appetite suppression

Precautions:

Not suitable for people sensitive to caffeine
May cause anxiety, tachycardia, or insomnia

Appetite Suppressants

They act on the nervous or digestive system to reduce the sensation of hunger. Their goal is to help you eat less without anxiety.

Common ingredients:

Glucomannan
Hoodia gordonii
5-HTP
Garcinia cambogia

Fat or Carb Blockers

They inhibit certain digestive enzymes, preventing part of the fats or carbs from being absorbed. They act like a partial barrier.

They’re less popular nowadays as they don’t promote a healthier relationship with food.

Stimulant-Free

Ideal for those who train at night or don’t tolerate stimulants. They often include:

L-carnitina
CLA (conjugated linoleic acid)
Mild herbal extracts

¿Do They Work? What the Science Says

The scientific evidence on fat burners is mixed but clear on one thing:
they work as support, not as a shortcut.

Real Effectiveness With Diet and Training

Caffeine and green tea extract have been shown to increase metabolism by 3–11% for a few hours after consumption.
L-carnitina may help people who are deficient or on low-calorie diets.
CLA has shown modest effects in reducing abdominal fat.
Other ingredients like capsaicin (spicy) have potential for mild effects.

Well-designed studies agree that real fat loss depends on maintaining a calorie deficit, and fat burners only enhance the result if everything else is done correctly.

What Results to Expect (and What Not)

You can expect:

A slight energy boost
Less appetite
Better performance during HIIT or cardio
Support during fat loss plateaus or definition phases

You should not expect:

Miraculous fat loss
Results without effort
Spot reduction of body fat

Risks and Most Common Side Effects

Like any supplement that acts on the nervous or digestive system, fat burners can have side effects, especially if overused or taken without control.

Common Side Effects:

Anxiety or irritability
Increased heart rate
Insomnia or trouble sleeping
Digestive discomfort
Headaches
Dizziness or jitteriness

In sensitive individuals or those with medical conditions, these effects can be more intense.

When Do They Make Sense and How to Use Them Wisely?

Not everyone needs a fat burner, but at certain moments, they can be a useful tool.

Get Informed Before Supplementing with The Nutrition Store

At The Nutrition Store we provide clear and up-to-date information about supplements like fat burners, so you can make conscious, evidence-based decisions.

Visit our store in Barcelona or explore more content on our website:
articles, comparisons, practical guides, and personalized advice.

Crema greixos: Funcionen o són una pèrdua de diners?