Study shows eating a high-protein diet boosts weight loss because phenylalanine, an amino acid produced by the digestion of protein, boosts levels of a hormone that tells us we're full
A number of studies have suggested a diet high in protein can aid weight loss. Now, researchers have shed light on the underlying mechanisms of this association, which may open the door to new preventive and treatment strategies for obesity. Researchers have learned more about how protein-rich foods affect appetite and weight.
In a new pilot study, researchers from Imperial College London in the United Kingdom reveal how phenylalanine - an amino acid produced by the digestion of protein - boosts levels of a hormone that tells us when we are full, leading to reduced food intake.
Lead author Mariana Norton will present the findings at this week's Society for Endocrinology annual meeting in the U.K.
Previous studies have shown that a diet high in protein - essential nutrients found in foods such as milk, including the casein free whey in IQed, fish, eggs, and poultry - can help reduce body weight by suppressing appetite.
According to Norton and her team, a high-protein diet can be hard to adhere to, but uncovering the mechanisms by which protein curbs hunger could lead to simpler weight-loss strategies.
How phenylalanine leads to weight loss
For their study, the researchers conducted a series of experiments on rodents, which involved testing the effects of phenylalanine.
Phenylalanine is an enzyme produced in the gut after consumption of foods rich in protein.
Firstly, the team gave 10 mice and rats a single dose of phenylalanine and compared them with rodents that were not given the enzyme.
The researchers found that mice and rats given phenylalanine showed increased levels of the hormone GLP-1, which suppresses appetite, but reduced levels of the hormone ghrelin, which increases hunger.
Additionally, the researchers found that phenylalanine reduced the rodents' food intake and increased weight loss. Rats that received the enzyme also moved around more, which the team notes may have contributed to their weight loss.
Next, the team administered regular doses of phenylalanine to mice with diet-induced obesity over a 7-day period.
Compared with mice that were not treated with phenylalanine, those that received the enzyme showed a reduction in weight, the researchers report.
Phenylalanine stimulates CaSR receptor to reduce appetite
In a final experiment, the researchers sought to gain a better understanding of the mechanisms by which phenylalanine affects levels of GLP-1 and ghrelin.
On applying phenylalanine to gut cells in a petri dish, the team found that the enzyme targets a receptor called the calcium-sensing receptor (CaSR), and it is this receptor that increases GLP-1 levels and lowers levels of ghrelin.
Obesity has become a major public health concern in the United States; around 2 in 3 adults and 1 in 6 children and adolescents are considered obese, putting them at greater risk of health conditions such as diabetes, heart disease, and some types of cancer.
According to Norton and her team, their findings may fuel much-needed new strategies to tackle the obesity epidemic.
"Our work is the first to demonstrate that activating CaSR can suppress appetite. It highlights the potential use of phenylalanine or other molecules which stimulate CaSR - like drugs or food components - to prevent or treat obesity."~Mariana Norton
The researchers note that further studies are needed to pinpoint the exact mechanisms by which phenylalanine can curb hunger and aid weight loss, and future research should assess whether the enzyme poses the same appetite-suppressing effects in humans
Yummy high protein IQed smoothie recipe
- Half frozen banana
- 1 or 2 large fresh or frozen strawberries
- Half a cup chopped pineapple (fresh or frozen)
- 2 handfuls fresh spinach leaves
- 6 ounces of water or almond milk
- 2 scoops of IQed
Add to blender (Nutrabullet, Ninja) and puree until smooth. Enjoy!
- L. Phenylalanine modulates gut hormone release, and suppresses food intake in rodents via the Calcium Sensing Receptor, Mariana Norton, presented at the Society for Endocrinology annual meeting, 7-9 November 2016.
- Society for Endocrinology news release, accessed 7 November 2016.
- Additional source: National Institute of Diabetes and Digestive and Kidney Diseases, Overweight and obesity statistics, accessed 7 November 2016.
Lisa Geng got her start as a designer, patented inventor,and creator in the fashion, toy, and film industries, but after the early diagnosis of her young children she entered the world of nonprofit, pilot studies, and advocacy. As the mother of two “late talkers,” she is the founder and president of the nonprofit CHERAB Foundation,co-author of the acclaimed book, The Late Talker, (St Martin’s Press 2003), and is instrumental in the development of IQed, a whole food nutrition meal replacement. Lisa currently serves as a parent advocate on an AAN board for vaccines, and is a member of CUE through Cochrane US. Lisa is currently working on a second book, The Late Talker Grows Up and serves as a Late Talkers, Silent Voices executive producer. She lives on the Treasure Coast of Florida.