That's why synthetic HGH gets a lot of hype: Some people think it can stave off age-related changes like bone loss, but you should be skeptical unless your doctor prescribes it for a specific condition like growth hormone deficiency, per the Mayo Clinic. There is little evidence that HGH can give healthy adults more youth or vitality. You should aim to include leucine as a part of a nutritious diet to support your overall health, but don't expect a leucine supplement to give you the fountain of youth.
There is not enough evidence to show that it does in a way that makes an impact on muscle recovery. Human studies on leucine for weight loss are limited. That said, some research shows that leucine plays a role in critical metabolic processes — and as noted before, it may help stabilize levels of blood glucose.
In fact, dietary levels of leucine might influence muscle mass maintenance during weight loss. However, there's no established leucine dosage for weight loss. It also doesn't necessarily mean you should go stock up on a leucine supplement for weight loss or expect leucine to burn fat for you. Fad diets and supplements typically don't work long-term for weight loss.
Instead, opt for an ongoing lifestyle that includes healthy eating habits, physical activity and realistic goals, per the U. Centers for Disease Control and Prevention. You may experience leucine side effects with a supplement, which is one reason it's typically best to get your nutrients from whole foods. According to the University of Rochester Medical Center, taking leucine supplements can have a number of unwanted effects:.
In general, supplements should not replace healthy, complete meals and it's important to eat a variety of foods, per the U. Even though leucine seems to increase insulin, which usually increases glucose uptake, leucine can also block glucose uptake.
Limited studies suggest that fasting increases blood levels of branched-chain amino acids BCAAs such as leucine. A study found that fasted animals with increased leucine concentrations did not uptake as much glucose as non-fasted animals thereby reducing energy production [ 37 ]. Some researchers suspect that this process of restricting pyruvate breakdown may explain why glucose uptake and energy production in the muscle of rats decreases after approximately 45 minutes [ 36 , 37 ].
In people that fasted, leucine supplements also reduced energy production because it inhibited the insulin-mediated glucose uptake by the muscles [ 38 ]. Some bodybuilders try to avoid this inhibitory effect of leucine on energy production by consuming a meal prior to workouts. Many studies did not specifically test for leucine but for all the branch chained amino acids BCAAs : leucine, isoleucine, and valine.
The efficacy and safety data on leucine is extremely limited. Clinical trials are lacking. In rats, leucine increased protein synthesis, while isoleucine actually had an inhibitory effect. These effects have not been confirmed in humans [ 2 ]. Branched-chain amino acids like leucine are possibly safe when appropriately used as oral supplements.
Theoretically, the blood-brain barrier competes for the absorption into the brain of branch-chained amino acids BCAA and aromatic amino acids ArAA , which are the precursors of serotonin.
This competition may, in theory, decrease serotonin production [ 39 ]. Leucine absorption into the brain may be influenced by diet; carbohydrate-rich, protein-poor diets increase BCAAs and decrease ArAAs in the brain, while a carbohydrate-poor, protein-rich diet may do the opposite [ 40 ].
Overdose can lead to increased blood ammonia levels; therefore, brain damage and liver disease [ 41 ]. Leucine supplementation lowers glucose levels, which can lead to unhealthy levels in people with:. The opinions expressed in this section are solely those of the users who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked.
SelfHacked does not endorse any specific product, service, or treatment. Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or another qualified healthcare provider because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.
Most users stated that the leucine was very helpful and that it was crucial to them in maintaining muscles after workouts. One note of caution is that almost every review bemoaned the taste of leucine supplementss. Many said that leucine was very bitter , but that it was worth it due to its positive effects. Some users saw some different side effects like loud ringing in the ears and increased anger that disappeared only after stopping the supplement.
Leucine is an essential, branched-chain amino acid. According to some evidence, leucine may enhance muscle recovery after intense exercise. Additionally, it may improve the symptoms of a movemet disorder called tardive dyskinesia and brain function in people with liver disease.
Leucine is likely safe when used by mouth at the recommended doses, but side effects are possible. Talk to your healthcare provider before supplementing. Purported Health Benefits of Leucine. Very high doses of leucine may cause low blood sugar hypoglycemia. It may also cause pellagra. Symptoms of this can include skin lesions, hair loss, and gastrointestinal problems. These include isoleucine and valine. Search Encyclopedia. Leucine Other name s : a-amino-isocaproic acid Unproven claims There may be benefits that have not yet been proven through research.
Open in a separate window. Figure 1. Leucine-Responsive Tissues Previous studies have demonstrated that numerous tissues respond to acute and chronic leucine treatment Figure 2. Figure 2. Central Effects of Leucine The CNS is an important site for regulating food intake, energy balance and glucose homeostasis [ 39 ]. Figure 3. Does Leucine Regulate Food Intake?
Table 1 Summary of the studies that investigated the effects of central leucine treatment on feeding. Table 2 Summary of the studies that investigated the effects of leucine supplementation in the diet on feeding. Decreased [ 63 ] Diet 12 weeks Healthy elderly men.
Energy intake and macronutrient composition were calculated from dietary intake records. No changes [ 68 ] Diet 6 weeks Previously obese rats No changes [ 21 ] Diet 6 weeks Regular and high-fat diets No changes [ 50 ] Diet 7 days HFD-fed mice; leucine produced similar effects as alanine supplementation. Table 3 Summary of the studies that investigated the effects of leucine supplementation in the drinking water or by other routes of feeding.
No change in HFD group. No leucine effect in mice fed an HFD. The Effects of Leucine on Body Composition, Obesity, and Energy Expenditure Despite the lack of evidence indicating that oral leucine intake affects food intake Table 2 and Table 3 , numerous studies have found that leucine supplementation reduces adiposity in specific conditions. Regulation of Glucose Homeostasis by Leucine Previous studies observed improved glucose tolerance in leucine-treated animals [ 51 , 54 , 71 , 78 , 80 , 81 , 82 ].
Concluding Remarks The potential effects of leucine supplementation are summarized in Figure 4. Figure 4. Conflicts of Interest The authors declare no conflict of interest. References 1.
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Chronic leucine supplementation increases body weight and insulin sensitivity in rats on high-fat diet likely by promoting insulin signaling in insulin-target tissues.
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