Red light therapy (RLT), also known as low-level laser therapy (LLLT) or photobiomodulation, is a treatment that uses low levels of red light to reportedly improve skin appearance. It is touted to reduce wrinkles, scars, redness, and acne and to treat other medical conditions. NASA originally began experimenting with red light therapy on plant growth in space and then to help heal wounds in astronauts. Like many developments, other potential uses began to be investigated.
The interest in red light therapy for weight loss has been increasing in popularity. However, there is currently no expert consensus on whether it actually works. While the available research generally shows that LLLT provides some fat loss benefits, the study designs are inconsistent. Additionally, a lack of data makes it difficult to say whether the results are long term or clinically relevant.
How Red Light Therapy Supposedly Works
Red light therapy is thought to work by acting on the "power plant" in your body's cells called mitochondria. With more energy, other cells can do their work more efficiently, doing things like repairing skin, boosting new cell growth, and enhancing skin rejuvenation. More specifically, certain cells absorb light wavelengths and are stimulated to work.
Red light therapy may work in skin health to:
- Stimulate collagen production, which gives skin its structure, strength, and elasticity.
- Increase fibroblast production, which makes collagen. Collagen is a component of connective tissue that builds skin.
- Increase blood circulation to the tissue.
- Reduce inflammation in cells.
Red Light Therapy and Fat Reduction: What the Studies Show
Due to inconclusive research, there is some controversy surrounding the question of whether red light therapy can help with weight loss.
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Studies include a pilot study from 2020 involving 60 adults with overweight. The results showed a modest 0.8-inch (2 cm) reduction in waist circumference following twice-weekly LLLT treatments over 6 weeks. However, there was no control group to compare the results with.
Another study, from 2017, specifically targeted abdominal girth using a combination of three wavelengths of low-level laser, including red, infrared, and blue. The study involved 18 females who each underwent a total of 12 LLLT sessions during the course of the study. The results showed significant reductions in upper, middle, and lower abdomen size, with all of the study participants experiencing positive results. The 3 wavelengths were applied sequentially, first, infrared laser, followed by red laser, and then blue LED. The irradiation time of each laser device was manually controlled with a timer. Each laser device was administered on 10 points of each quadrant of the abdomen. The first point which was 3 cm apart from the umbilicus was chosen and then 3 cm apart laser device was used from one treatment point to another. Laser device was positioned at contact mode with a moderate pressure on tissue and titled at a 90º angle. Time of irradiation was 15 seconds per point for each device (1.5 J/point IR + 1.5 J/point red + 45 J/point the blue LED, in total 48 J IR + RED + Blue LED per point). Total energy was 480 J/quadrant and 1920 J/session. Girth of the abdomen at the site of umbilicus was noted as the middle abdomen, the girth of 4 cm above the umbilicus was measured as the upper abdomen and 4 cm and below the umbilicus was measured as the lower abdomen. Statistical analyses revealed that upper abdomen size significantly decreased from pre- (91.86 ± 11.16) to post-LLLT (87.41 ± 10.52) (P < 0.001). Middle abdomen size showed significant reduction from pre- (97.02 ± 8.82) to post-LLLT (91.97 ± 8.49) (P < 0.001).
In 2018, researchers looked into the potential benefits of LLLT with exercise training to reduce body fat. The study involved 49 females with obesity aged 20-40 years, divided into intervention and sham groups. The participants underwent three sessions per week of exercise training with phototherapy after exercise for 4 months. All participants experienced improvements. However, only those who received LLLT showed reduced interleukin-6, which is a marker of immune health, and increased WNT5 signaling, which is needed for the development of healthy cells. This group also experienced bigger changes than the sham group in relation to:
- fat mass
- insulin
- HOMA-IR, which is a measure of insulin resistance
- FGF21, which regulates carbohydrate and fat metabolism
Another study from 2017 also found that receiving LLLT in addition to treadmill walking resulted in a greater reduction in abdominal fat and body weight. However, one study actually found an increase in fat tissue thickness in 8 out of 17 participants.
Researchers still need to work out the definitive mechanism of action behind LLLT. However, it might relate to the absorption of laser light into the adipocytes, which leads to increased cyclic adenosine monophosphate production, a type of cell signal or messenger. This then stimulates an enzyme called cytoplasmic lipase, which converts triglycerides to fatty acids and glycerol. These substances can pass through pores, causing the adipocytes to shrink.
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Additionally, one animal study from 2018 found that infrared photobiomodulation therapy, which is another name for LLLT, improved glucose metabolism and insulin regulation in the fat tissue of mice with obesity caused by a high fat diet. Photobiomodulation has also been shown to increase muscle mass gained after training.
LLLT as an Adjuvant to Liposuction
In 2000 a new technique was introduced by Niera et al. which utilized LLLT as an adjunct to liposuction. They used a dose rate that caused no detectable temperature rise in the tissue and no macroscopic changes in the tissue structure were observed. This application of LLLT was derived from prior investigations of LLLT in wound healing, pain relief, and edema prevention. Evidence existed that wavelengths between 630 and 640 nm were optimum for biomodulation and these wavelengths were therefore used for LLLT-assisted lipoplasty. It was applied to the surface of the skin before liposuction, with the intent to emulsify the fat thereby softening the area prior to aspiration. A placebo-controlled, randomized, double-blind, multicentered clinical study was performed to evaluate the clinical utility of this application as an adjunct to liposuction and the results suggested that laser therapy decreased operating room times, increased the volume of fat extracted, less force was required by the physician to breakup fat, and the recovery for patients was significantly improved.
Niera et al. studied samples of human adipose tissue from 12 lipectomy patients who were operated with and without tumescent technique and externally irradiated with a 635-nm, 10 mW diode laser with total energy values of 1.2-3.6 J/cm2 for 0-6 minutes. The group found out that the tumescent technique had synergistic effects, facilitated laser light penetration, and intensity, thus improved fat liquefaction. While after 4 minutes of laser exposure 80% of the fat was released from the adipose cells, after 6 minutes of laser exposure almost all of the fat was released from the adipocyte. When no tumescent solution was applied and adipose tissue was exposed to laser beam for 4 and 6 minutes, scanning electron microscope (SEM) and transmission electron microscope (TEM) images after 6 minutes laser exposure in samples taken without tumescent solution corresponded to those observed in samples exposed to 4 minutes of laser irradiation with equal parameters and the tumescent solution.
LLLT and Cellulite Reduction
Even though etiology of cellulite remains controversial, it manifests itself at the histological level not only by the presence of thinner, more radially oriented supporting fibrous septae in the deep subcutis, but also by an irregular dermohypo-dermal interface produced by herniation of subdermal fat into the reticular and papillary dermis.
Sasaki et al. conducted a double-blinded study among nine female volunteers to evaluate the efficacy of phosphatidylcholine-based anticellulite gel (active gel) in combination with a LED at wavelengths of red (660 nm) and near-infrared (950 nm), a deeper penetrating wavelength, for treatment of cellulite. Study subjects were treated twice daily for 3 months with an active gel on one thigh and placebo gel on the other thigh. Twice a week, each thigh was exposed to 15 minutes of LED with a total of 24 treatments. Digital ultrasound at the dermal-adiposal interface revealed not only a signifi-cant reduction of subcutaneous fat immediately below the dermis but also less echo-like intrusions were observed in the dermal layer of active gel and LED treated thighs.
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Safety and Side Effects
The 2017 study mentioned above reported no side effects relating to the LLLT in any of the following three treatment frequencies:
- three times per week for 4 weeks
- twice per week for 6 weeks
- once per week for 12 weeks
However, another study from 2017 observed side effects of LLLT in two participants. Both people developed broken skin, one at their appendectomy scar and the other on their lower back. The researchers concluded that devices applied directly to the skin are less safe than devices with treatment panels separated from the skin.
Red Light Therapy Devices
There are many different types of red light therapy devices, some of which can be used at home. But home devices are usually less powerful than those used in clinics and may be less effective or take longer to work. Red light therapy devices include:
- Red light therapy mask: This fits over your entire face and has red LED lights on the inside, pointed toward your skin. It is designed to be worn for a short length of time several times a week. It's used as a treatment for acne, wrinkles, or other facial skin concerns.
- Red light therapy bed: This looks like a tanning bed but has red LED lights instead of UV lights. It is big enough for you to lie down inside, and your whole body is exposed to red light.
- Red light therapy panel: This is a panel of red LED lights that you can mount on a wall or place on a table, either at a clinic or home. Panels range in size from small to large. Small panels are used for targeted areas such as your face, and large panels can target larger areas of your body.
- Red light therapy wand: These are handheld devices that have red LED lights at one end. You use them by moving the wand over your skin in the areas that you want to treat. They are used to treat very small areas, such as the back of the hands, one knee, or a particular spot on the face.
Alternative Approaches to Weight Management
As the CDC explains, healthy weight management is about lifestyle rather than a specific diet or program. It is about establishing healthy eating patterns in combination with regular physical activity and stress management.
A review in Nutrients from 2020 reported that healthier alternatives to the Western diet tend to feature more plant-based foods, such as:
- fresh fruits and vegetables
- whole grains
- legumes
- seeds and nuts
These diets include the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, and the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet. They also tend to be lower in animal-based foods, especially fatty and processed meats.
Additionally, the American Association of Clinical Endocrinologists and the American College of Endocrinology recommend moderate-intensity aerobic exercise for at least 150 minutes per week for the medical care of people with obesity. They note better outcomes with increasing intensity and amounts of exercise.
There is also evidence that actively managing stress can help a person manage their weight. For instance, in one study from 2018, 45 adult participants received standard instructions for a healthy lifestyle. Of these, 22 people in the intervention group also attended an 8-week stress management program. This involved breathing from the diaphragm, doing progressive muscle relaxation, doing guided visualization, and receiving instructions about healthy dietary habits. The intervention group achieved a significantly greater reduction in BMI compared with the control group, with losses of 3.1 kilograms per square meter (kg/m2) in the intervention group compared with 1.74 kg/m2 in the control group.