How Red Light Works For Weight Loss: Clinical Trial Results

The Centers for Disease Control and Prevention classifies over 70% of U.S. adults as overweight and over 40% as obese [1]. These numbers continue to rise, and even when some manage to lose weight, they almost always gain it back over time [2]. 

Often the pursuit of the cosmetic benefits of weight loss far outweigh the medical benefits associated with weight loss. Therefore, more women than men seek help for weight loss, although the health problems associated with being overweight are the same for men and women.

Weight loss should be seen not only as a cosmetic effect but mainly as a concern for health. It is important to approach weight loss responsibly and cautiously. That is why we have studied the scientific evidence for the effectiveness of a natural and non-invasive aid in weight loss — red light therapy. And also highlighted the opinions of researchers and doctors about the causes and effects of being overweight. 

How Light Therapy Affects Fat Loss

Before we consider the effects of red light therapy on body correction, let's understand what red light therapy is.

What Red Light Therapy Is

Red light therapy (RTL) is also known as low-level laser therapy (LLLT), biostimulation (BIOS), photon stimulation, or simply light therapy. 

RTL is a non-invasive therapy that uses red and near-infrared light. Light in this range is called “weak light” because it operates at a lower energy density than other types of laser therapy [32].

Red light waves are consumed by the skin to a depth of about 1-2 inches, thereby affecting the body on a cellular level. But this process is not felt or painful because it does not produce heat.

During its existence, red light therapy has undergone hundreds of clinical studies, which testify to its various therapeutic capabilities and safety. Because of this, it has had medical applications for decades. But can it help in the fight against excess weight? And if so, how? What research is there in this area of application?

The effect of red light on fat loss. Clinical research response

A person's weight depends on many factors. Focusing on diet and exercise on a “calories in, calories out” basis is an oversimplification of how the body processes fat. Other key aspects of weight control include hydration, sleep, hormones, circadian rhythms, and how the body processes inflammation.

Researchers state that light therapy provides many ways to lose weight as well as reduce cellulite. RLT can activate cells in your body affecting different aspects of health and help the body's natural fat-burning mechanisms work more effectively. 

Fat Cell Reduction

RLT affects the skin by penetrating the adipocytes (the fat cells in our body that store fat). When this happens, the combined efforts of red and near-infrared light form temporary pores in the adipocytes, allowing toxins and fats (lipids) to leak out and eventually leave the body through sweat.

One study showed that as little as four minutes of exposure to 635 nm red light caused 80% of lipids to be released from fat cells, and by six minutes almost all of the fat was released [33].

Also, a 2018 study showed that red light therapy at a wavelength of 650 nanometers causes lipolysis, which is the breakdown of lipids/fat in the subcutaneous fatty tissue of the body [3]. This leads to fat loss and the formation of body contours.

Read also about Ultrasonic Cavitation technology based on light therapy that helps to burn the fat.

Appetite suppression

Red light can affect hunger levels by controlling the hormones leptin and ghrelin. Leptin is an appetite-reducing hormone and ghrelin is the opposite, an appetite-enhancing hormone.

In 2012, the International Journal of Endocrinology published a study that showed for the first time that red light at 633 nm can affect the concentration of leptin and ghrelin [4]. In this study, researchers studied participants with poor sleep habits. Decreased sleep often leads to increased ghrelin production and decreased leptin levels, which often leads to weight gain.

Their study showed that exposure to red light significantly increases leptin levels while decreasing ghrelin levels. This reduction in hunger levels can have a big impact on those trying to follow a low-calorie diet for weight loss, helping to reduce hunger and the desire to snack.

By systematically controlling these hormones, you can control eating habits, preventing fat accumulation in your body. This is a healthy, non-invasive approach to controlling and maintaining weight, especially after you've lost a few pounds.

Improved sleep

Sleep quality affects virtually every aspect of our health, including weight and fat loss. If you are struggling with weight problems, poor sleep can be a significant factor.

One cause of sleep disorders is chronic stress, which increases weight gain by stimulating cortisol production and disrupting metabolic regulation of the nervous system. In other words, poor sleep can lead to complications in digestion, metabolism, and weight

Several studies have provided promising evidence that red light therapy helps improve sleep.

One of them, a 2012 study showed that RLT before bedtime increased melatonin*, improved sleep quality, and increased daytime endurance, giving you more energy for your exercise program the next day [5]. 

*Melatonin is a hormone that regulates the sleep-wake cycle. Melatonin production increases at night, which contributes to sleepiness and vice versa.

Also, a 2019 study [6] showed that red light prevents sleep inertia. Sleep inertia is the feeling of weakness you experience after waking up that lasts from 1 minute to 3 hours.

Read more in our article “Red Light Therapy for Sleep Disorders”

Increasing muscle mass

Muscles are known to require more energy (each pound of muscle can burn 50 calories a day at rest). This means that the more muscle you have, the more calories you will burn, even when you are not exercising.

There have been many clinical trials of the effects of light therapy on human muscle tissue. They have included both untrained and trained healthy people or athletes [7, 8, 9, 10, 11, 12, etc]. 

A) Example of muscular pre-conditioning irradiating multiple sites or points on the biceps brachii. B) Exercise test on a Scott bench.
Source: PubMed Central

A review of such studies suggests that there are currently more positive effects in favor of photobiomodulation than contradictory or negative results [13]. Subjects exposed to the red light before and after exercise recovered their muscles faster and increased their muscle growth

Besides, if all the positive results achieved in the lab continue to show comparable improvements in athletic performance in the real world, then photobiomodulation will become very popular, mostly among high-level athletes.

Find out more about Laser Lipo Machines — technology that helps with weight loss and increases muscle mass.

Reduces cellulite and strengthens the skin

The effects of red and near-infrared light therapy also promote weight loss by reducing the fat pockets that cause cellulite on the surface of the skin.

Cellulite is an excess of subcutaneous fat or fat that is just under the skin. It is caused by the accumulation of unhealthy collagen and elastin and excess fat in layers of skin.

In 2011, a controlled study of two groups of 10 women was conducted: one group simply exercised on a treadmill, and the second group exercised on a treadmill and received light in the near-infrared spectrum with a wavelength of 850 nm [14]. The group that used both forms of treatment achieved a reduction in cellulite in the buttocks and thighs, whereas the group that only used the treadmill did not. 

Red light therapy replenishes collagen production by increasing fibroblast growth factor. Fibroblasts are not only responsible for collagen production, but also increase its movement through the cell walls, which ultimately tightens the skin.

These are the main ways in which red light therapy can be beneficial for weight loss. But the effects of RLT on the body don't end there. You can read about other scientifically proven effects in our research:

Targeted weight loss 

Each person loses fat in his or her way: some may accumulate more fat in the belly, while others struggle with their hips or arms. Therefore, more often than not, those who want to lose weight highlight their particular “problem areas” and some areas they wish to leave unchanged.

The pursuit of targeted fat removal has led to the popularity of body contouring surgery. Although we all understand the disadvantages of such procedures, they are in demand because surgery is the only way to completely target fat removal.

Red light therapy, unlike surgery, cannot help get rid of fat only in the targeted areas. However, studies show that RLT can be used to target areas commonly referred to as “problem areas” (such as the abdomen and thighs).

Back in 2009, a study [29] was conducted to evaluate the use of 635 nm and 17.5 mW of output power for body contouring, namely the waist, hips, and thighs. According to the results of the study, the participants in the treatment group had a total reduction of -3.51 inches and placebo -0.684 inches

A 4-week study of the effectiveness of red light therapy for point fat reduction in 40 healthy men and women showed a safe and significant loss of waist circumference (about 1 inch on average) [30]. Subjects achieved these results without any changes (diet or exercise).

After the results were obtained, there was still doubt as to whether the volume change was the result of a simple redistribution of liquid or fat. To clarify the results, a study [31] was conducted in which 689 participants received a total of six LLLT procedures within 2 weeks. Before and after the study, participants were given their body measurements (waist, hips, arms, knees, neck, and chest).

Participants showed an overall average volume decrease of 5.17 inches at all points. Each measured area, including untreated areas, showed a significant volume decrease. This indicates that the changes were not related to the movement of fluid or fat.

What You Need to Know About Overweight and Obesity

Being overweight occurs when the body consumes more calories than it can burn. But there is much more science behind fat.

To determine the difference between simply being overweight and obesity, body mass index (BMI), waist circumference, and assessment of risk factors and comorbidities are usually assessed.

The Body Mass Index Formula

Metric Units:
BMI = Weight [kg] / (Height [m] x Height [m])
English Units:
BMI = Weight [lb] / (Height [in] x Height [in]) x 703

The BMI between 25 and 29 is considered overweight, and BMI over 30 is considered obese. But also with overweight and obesity, even a little weight loss can improve your health. 

The Body Mass Index

Consequences of Being Overweight

The National Center for Health Statistics reports that over 70% of U.S. adults are overweight and over 40% are obese [15]. These percentages continue to rise, and the pandemic has made the situation even worse.

Ada Stewart, MD, FAAFP, has extensive experience with obesity and its effects on patients. About 75 percent of the patients she treats at Columbia Federal Medical Center are overweight or obese, and most have at least one co-morbidity [16].

In general, obesity is defined as a condition in which the natural energy storage in adipose tissue increases to such an extent that it becomes a risk factor for certain health conditions or increased mortality.

Several studies show that excess body weight predisposes to cardiovascular disease, type 2 diabetes, hypertension, sleep apnea (stopping breathing for more than 10 seconds), osteoarthritis, and many other effects [17, 18, 19]. Also, recent studies have shown that obesity increases the risk of death from Covid-19 by almost 50% [20].

Causes of Overweight

To combat any problem, it is important to understand its causes. To determine what physicians consider to be the main causes of obesity, a survey led by Associate Professor Dr. Sarah Bleich [21] was conducted. Five hundred primary care physicians participated in the survey. Physicians had to rank the major factors affecting a patient's weight.

Based on the results of a survey of physicians, here's a ranking of the causes of obesity:

  1. Overeating 
  2. Restaurant meals and fast food
  3. Sugar drinks
  4. Genetics
  5. Metabolic disorder

Only 19 percent of physicians rated genetics, and 12 percent rated metabolic disorders as significant causes of obesity. Obesity rates have increased dramatically only in the last 20-30 years, and genetic changes in human populations are too slow, so genetics cannot be an explanation for the obesity epidemic.

Nevertheless, differences in how people respond to the same environment suggest that genes do play a role in the development of obesity. Not all people living in the same environment will become obese, and not all obese people will have the same health problems [22, 23].

A person with a genetic predisposition in the proper environment–and we have in the United States–has a greater chance of becoming obese,” says Caroline M. Apovian, M.D., director of clinical research at Obesity Research.

Between 1986 and 2000, the prevalence of severe obesity [BMI ≥40 kg/m2] increased 4-fold, from 1 in 200 Americans to 1 in 50. Adults with a BMI ≥50 kg/m2 (supersaturated) increased 5-fold [24, 25]. Besides, the prevalence of overweight in pediatric age groups has nearly tripled in the past 30 years [26]. And currently, about 9 million children over 6 years of age are considered obese [27].

These statistics show that obesity is not really a genetic problem. It should be encouraging because most of the obesity epidemic is preventable. Some things make a difference in a patient's life that can contribute to the reduction of excess weight.

To a greater extent, various environmental and behavioral factors cause the problem of obesity. So, to the factors listed above, it is also important to include insufficient sleep and physical activity [28].


There aren't many significant studies yet that directly investigate the effects of red light therapy on weight loss. But there are enough related studies that scientists are optimistic that red light therapy has a positive effect on reducing body fat.

It has been proven that light therapy can affect appetite, break down lipids/fat in the body's subcutaneous fat, improve sleep quality and stimulate cellular energy, which leads to improved overall body organ function and increased metabolism. Also, red light therapy combined with exercise reduces fat deposits and increases muscle mass more effectively.


🎈 Is red light therapy effective for weight loss?

Several studies show that red light therapy has a positive effect on reducing body fat by affecting the body at the cellular level.

🎯 Is targeted weight loss possible with red light therapy?

Completely targeted fat removal is not possible by any means other than surgery. But some studies show the potential of using red light therapy to target “problem” areas.

🖍️ Is the weight loss permanent with red light therapy?

Continued red light therapy combined with a healthier lifestyle can help you maintain your desired weight, as well as spot, treat persistent problem areas. But no procedure or treatment will result in permanent loss of excess fat without changing the habits that caused the excess weight.

🍊 Can red light therapy affect cellulite?

Yes, RLT promotes weight loss by reducing the fat pockets that cause cellulite on the surface of the skin. RLT also replenishes collagen production and increases its movement through the cell walls, which ultimately tightens the skin.

🎭 Are there any side effects of red light therapy?

Red light therapy is a safe, non-invasive procedure. But if you have a hypersensitivity to light, you should be careful with red light therapy. Too intense light can cause some short-term effects.

Jose Diego Mier

Dermatology Expert

Dr. Jose Diego Mier is a board-certified dermatologist with over a decade of experience in light therapy, dermatology, and skin care. As the founder of the Heliotherapy Research Institute, Dr. Mier has dedicated his career to the study and application of light-based therapies for various skin conditions, including acne, psoriasis, eczema, and skin aging. He is renowned for his extensive research contributions, numerous publications in leading dermatology journals, and his work has been recognized with awards for excellence in research and innovation. He has been invited to speak at national and international conferences, sharing his expertise and insights on light therapy and skin care.

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