Researchers tested whether adding glycine, a building block protein, could help people with severe obesity. Nineteen participants took glycine supplements for two weeks. The study found that glycine levels in their blood increased, and their triglycerides (a type of fat in the blood) decreased. Their liver health markers also improved. While participants didn’t lose weight during the short study, the results suggest glycine might help their bodies work better at removing harmful substances and protecting their liver. Scientists think this could be an important discovery for treating obesity-related liver disease.

The Quick Take

  • What they studied: Whether taking glycine supplements could fix a deficiency found in people with severe obesity and improve how their bodies process harmful substances
  • Who participated: 19 adults with severe obesity (average BMI of 38.3), meaning they were significantly overweight according to standard health measurements
  • Key finding: After two weeks of glycine supplements, participants had higher glycine levels in their blood, lower triglycerides (a harmful fat), and improved liver health markers. No weight loss occurred during the study period.
  • What it means for you: This small study suggests glycine supplements might help people with severe obesity improve their blood fat levels and liver health, but much more research is needed. This is not yet a proven treatment and should not replace medical advice from your doctor.

The Research Details

This was a small exploratory study with 19 people who had severe obesity. Participants took glycine supplements (a protein building block) at a dose of 100 milligrams per kilogram of their body weight each day for two weeks. Researchers measured various substances in their blood and urine before and after the treatment to see what changed.

The study was designed to test whether glycine supplements could reverse a deficiency that scientists noticed in people with obesity. Glycine is important for several body processes: helping make a protective substance called glutathione, removing toxic byproducts through a process called glycine conjugation, and supporting a metabolic pathway called the 1-carbon cycle.

Because this was an exploratory study, it didn’t have a control group (people taking a placebo or dummy pill). This means we can’t be completely sure the changes were caused by glycine alone, though the results are still interesting and worth investigating further.

Understanding how glycine affects people with severe obesity matters because obesity is linked to serious health problems, especially liver disease. If glycine supplements could help improve liver health and blood fat levels, it might offer a new treatment option. This exploratory approach helps scientists decide whether larger, more rigorous studies are worth doing.

This study is small (only 19 people) and short (only two weeks), so the results are preliminary. It lacks a control group, which means we can’t be certain the changes were caused by glycine rather than other factors. However, the study was published in a respected scientific journal and measured many different markers in the blood and urine, which strengthens the findings. The researchers were transparent about what they found and called for more research, which is a good sign of scientific integrity.

What the Results Show

The main finding was that glycine supplements successfully increased glycine levels in participants’ blood. This is important because people with severe obesity typically have low glycine levels, and the supplement corrected this deficiency.

Participants also showed increased excretion of several compounds in their urine (isobutyrylglycine, tigylglycine, isovalerylglycine, and hexanoylglycine). These compounds are created when the body uses glycine to remove harmful metabolic byproducts—essentially, the body’s detoxification system was working better.

Blood triglycerides (a type of fat linked to heart disease) decreased significantly. This is important because people with obesity often have high triglycerides. Additionally, liver enzymes (aminotransferases) decreased, suggesting the liver was healthier. A marker called the glutamate-serine-glycine index, which indicates liver disease risk, also improved.

The study found that glycine supplements increased levels of several other important compounds: serine, homocysteine, cysteine, and folate. These are all part of the 1-carbon cycle, a metabolic pathway important for many body functions including DNA production and cell division. Surprisingly, glutathione (a protective antioxidant that glycine helps make) didn’t increase, even though glycine levels did. This suggests the body may have used the extra glycine for other important processes first.

This study builds on previous research showing that people with obesity have lower glycine levels than people of normal weight. Earlier studies suggested this deficiency might contribute to metabolic problems and liver disease. This is the first study to test whether supplementing glycine could reverse these problems. The findings align with what scientists expected based on glycine’s known roles in the body, which adds credibility to the results.

The biggest limitation is the small sample size (only 19 people) and short duration (two weeks). We don’t know if benefits would continue longer or if they would be seen in larger groups. The study had no control group, so we can’t be completely certain the changes were caused by glycine rather than other factors like diet changes or placebo effect. The study also didn’t measure weight loss or other important health outcomes. Finally, all participants had severe obesity, so we don’t know if these results would apply to people with mild or moderate obesity.

The Bottom Line

Based on this preliminary research, glycine supplementation is not yet recommended as a standard treatment. The evidence is promising but limited. Anyone interested in trying glycine supplements should first discuss it with their doctor, especially if they have liver disease or take medications. More research with larger groups and longer timeframes is needed before making any treatment recommendations. (Confidence level: Low—this is early-stage research)

People with severe obesity and liver disease should be most interested in this research, as should their doctors. People with metabolic syndrome or high triglycerides might also find this relevant. However, this research is too preliminary for anyone to make treatment decisions based on it alone. People taking medications or with existing health conditions should definitely consult their doctor before trying supplements.

In this two-week study, changes in blood markers appeared quickly. However, we don’t know if these improvements would continue, get better, or lead to actual weight loss or disease improvement over months or years. Real-world benefits might take much longer to appear, if they appear at all.

Want to Apply This Research?

  • If a user’s doctor approves glycine supplementation, track daily glycine intake (in grams), blood triglyceride levels (if tested), and liver enzyme levels (if tested). Also track energy levels and any digestive changes.
  • Users could set a daily reminder to take glycine supplements at the same time each day. They could also log their supplement intake in the app and note any changes they observe in how they feel, their energy levels, or their digestion.
  • Establish a baseline by getting blood work done before starting (triglycerides, liver enzymes). Schedule follow-up blood tests every 4-8 weeks to monitor changes. Use the app to track consistency of supplement use and correlate it with any health improvements noted by their doctor.

This research is preliminary and based on a small study of only 19 people over two weeks. Glycine supplementation is not an approved medical treatment for obesity or liver disease. Do not start taking glycine supplements without consulting your doctor first, especially if you have liver disease, kidney disease, or take medications. This article is for educational purposes only and should not replace professional medical advice. Always speak with a healthcare provider before starting any new supplement or treatment.