Leucine and how the body handles fat and energy
What it found
Leucine and its breakdown products may help the body burn more fat and store less, according to studies in people, animals and cells.
The authors say more work is needed to understand exactly how.
What they found
Studies in people
HMB in people
In human trials, HMB taken during endurance training helped reduce fat mass. HMB supplements also lowered triglycerides and LDL cholesterol in people.
Animal and lab studies
Browning of fat
Leucine supplementation in animals increased a brown-fat gene in white fat tissue nearly fourfold and helped develop beige fat cells, which may help burn more energy.
Muscle and energy
In mice and cells, leucine moved energy from fat stores to muscle, increased fat burning in muscle, and improved insulin sensitivity. One mouse study found a 25% drop in body fat.
Livestock use
In pigs and chickens, leucine or its metabolites have been tested to improve growth and carcass quality by changing fat deposition. These findings are from farm animals, not people.
Studies in people and animals
Fat burning in fat tissue
In lab tests and animal studies, leucine has been reported to stop fat being made, boost fat breakdown and fatty acid burning, and increase leptin release from fat cells. This may help reduce body fat.
Gut bacteria
Leucine may change the mix of gut bacteria and the short-chain fatty acids they make, which in turn may affect fat metabolism. But how leucine targets gut bacteria to control fat is still unclear.
What the authors conclude
“However, it is necessary to carry out additional experiments to elucidate its regulatory mechanisms.”
Also in their conclusions
- They say leucine and its metabolites have a promising role in fat and energy metabolism by increasing fatty acid oxidation and improving metabolic health.
- They suggest leucine may help against aging, neurodegenerative diseases, obesity, diabetes and cardiovascular disease, and could be a functional additive for human health and livestock production.
- They advise that more experiments are needed to explain exactly how leucine works.
How it was done
The authors wanted to pull together recent findings on how leucine affects fat metabolism and energy balance, and whether it could be useful against obesity and related conditions.
They reviewed studies in people, animals and cells that looked at leucine or its metabolites (KIC and HMB) and their effects on fat metabolism, energy use, mitochondria, gut bacteria and livestock production.
What it can’t tell you
- Many of the findings come from animals or cells, so they cannot show what happens in people.
- The review cannot prove that leucine causes fat loss or health improvements in people, only that studies have found links.
- It is still unclear whether the effects come from leucine itself or from its breakdown products KIC and HMB.
Who paid
- Funding
- Funded by National Basic Research Program of China (973 Program); National Natural Science Foundation of China; Science and technology projects of changsha; STS regional key projects of Chinese Academy of Science; Youth Innovation Team Project of ISA, CAS; Earmarked Fund for China Agriculture Research System (from the PubMed record).
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- Institute of Subtropical Agriculture, China; University of Chinese Academy of Sciences, China; Hunan Normal University, China
The paper
- Title
- Leucine Supplementation: A Novel Strategy for Modulating Lipid Metabolism and Energy Homeostasis
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Zhang L, Li F, Guo Q, et al (2020). Leucine Supplementation: A Novel Strategy for Modulating Lipid Metabolism and Energy Homeostasis. Nutrients. doi:10.3390/nu12051299Free full textPubMed 32370170DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error