For several months now, I’ve been engrossed in my study of the groundbreaking weight-loss medications, Ozempic and Wegovy. These medications contain semaglutide, a powerful compound that suppresses hunger like a fly swatter obliterates a mosquito. People who have tried these drugs rave about the fact that their constant cravings for food have vanished, allowing them to eat less frequently. It seems that the medication has a remarkable ability to silence what many describe as the “food noise” in their minds – that incessant internal chatter urging them to eat.
As I delved deeper into my research on Wevgovy and Ozempic, I stumbled upon a fascinating revelation. It turns out that the drugs mimic GLP-1, a hormone naturally produced by our bodies during meal times. This discovery led me to ponder whether we could increase our levels of GLP-1 simply by modifying our diet. To my astonishment, esteemed metabolic diseases researcher Frank Duca at the University of Arizona confirms that it is indeed possible to enhance our body’s production of GLP-1 through diet.
Duca reveals that one key food that triggers the release of GLP-1 is a nutrient that many Americans struggle to consume in sufficient quantities, despite its myriad health benefits: fiber. “Whenever my family finds out that I’m studying obesity or diabetes, they always ask me about the wonder drug or the secret remedy,” Duca explains. “And my response is always the same: ‘Eat more fiber.'”
However, not all types of fiber are created equal. Duca and other researchers have discovered that certain fibers are more potent than others in triggering the release of GLP-1 and regulating hunger. “We’re observing that many companies are adding fiber to their products, but often it’s not the type of fiber that offers optimal benefits,” Duca warns.
To comprehend why fiber plays such a crucial role in GLP-1 production, let’s examine what happens when we consume a low-fiber meal. Suppose you wake up feeling famished and decide to have two slices of white bread and a fried egg for breakfast. As the digested food makes its way into your small intestine, the nutrients – carbohydrates, fats, and amino acids – set off a chain reaction in your blood and brain. “The food activates cells in your intestine, and these cells release a multitude of hormones,” explains Sinju Sundaresan, a gut physiologist at Midwestern University. About 20 of these hormones, including GLP-1, are known as satiation hormones. Sundaresan elucidates, “They signal your body to start absorbing nutrients and suppress hunger.”
Thus, you slow down your eating pace and eventually cease because you feel satisfied. At this juncture, GLP-1 goes into action. It stimulates the secretion of insulin and slows down the movement of food from your stomach to your intestine, ensuring that the fuel is not consumed too quickly, as Gary Schwartz, a renowned neuroscientist specializing in eating and appetite, explains. Additionally, GLP-1 likely activates neural pathways in the brain by stimulating the nerves lining the gut. Schwartz elaborates, “These neurons gather information from the gut and signal all the way to the brain stem, where another pathway for GLP-1 is located.”
However, the actions of GLP-1 are fleeting. “Once the hormone enters the bloodstream, it rapidly degrades,” reveals Darleen Sandoval, an integrated physiologist at the University of Colorado who has devoted years to studying GLP-1. “By the time it reaches the heart and circulates throughout the body, there’s very little of it left,” she states. Hence, one to two hours after consuming a low-fiber breakfast, GLP-1 levels plummet, and hunger re-emerges by lunchtime.
This is where GLP-1 differs significantly from semaglutide, the active ingredient in weight-loss medications. While GLP-1 only lingers in the bloodstream for a few minutes, semaglutide persists for days. This extended presence allows the drug to directly suppress appetite and cravings by acting on the brain, says Sandoval. That explains why individuals taking these drugs experience such remarkable weight loss. “In mice or rats, we can administer GLP-1 directly into their brains, and it completely eliminates their desire to eat,” Sandoval reveals.
Now, let’s revisit our breakfast scenarios. What if, instead of consuming white bread, you opt for two slices of rye bread containing 8 to 10 grams of fiber? It turns out that the addition of substantial fiber content presents another opportunity for your intestines to release GLP-1, many hours after your meal. Satiation hormones remain active for longer periods when fiber is involved.
Our bodies lack the capacity to break down fiber completely, so it traverses through our small intestines largely unchanged until it reaches our colons, typically 4 to 10 hours after consumption. Inside the large intestine, fiber encounters a bustling community of microbes capable of digesting it. Bacteria in your colon break down certain dietary fibers into smaller molecules that can stimulate the release of GLP-1 as well as another hormone called PYY (peptide YY), which reduces appetite. These smaller molecules can independently suppress hunger and have been associated with lower body weight and improved glucose regulation.
Due to this delayed release of GLP-1 and PYY, cravings between meals subside, and the overall desire to consume the next meal diminishes. “PYY controls satiety – the time interval between meals,” elucidates Frank Duca of the University of Arizona. “The release of PYY, alongside GLP-1, can prolong the duration between meals,” he adds. These hormones may even influence the amount consumed during the subsequent meal. “This phenomenon is known as the second meal effect,” explains Edward Deehan, a nutritional microbiologist at the University of Nebraska-Lincoln. “If you consume a sizable amount of fiber in one meal, by the time it reaches your colon, it coincides with your next meal. Consequently, you may experience improved insulin responses, enhanced satiety, or a heightened feeling of fullness,” Deehan details.
Not all fiber, however, yields the same results. To obtain this extra surge of satiation hormones, it is essential to consume fermentable fiber, which can be broken down by bacteria. These fibers are aptly named because they undergo fermentation by gut bacteria, much like yeast fermenting barley to produce beer. Scientists such as Duca are currently studying which fermentable fibers are most effective at suppressing appetite and facilitating weight loss. “The agricultural community in the U.S. should prioritize the cultivation of grains rich in these fibers,” Duca ardently suggests. In one initial study involving mice, Duca and his team found that a particular fiber called beta-glucan, found in barley, induced the greatest weight loss in obese animals. “At face value and in our specific settings, beta-glucan proved to be the sole effective fiber,” Duca divulges. Beta-glucan is also present in oats and rye. Studies conducted on humans have also demonstrated that beta-glucan fiber may increase insulin sensitivity, lower blood pressure, and enhance satiation between meals. Other fermentable fibers include dextrin in wheat, oligosaccharides in beans, peas, and lentils, as well as pectin in apples, pears, and green bananas.
If your current diet lacks fiber, Duca advises not to worry excessively about the specific fiber you begin incorporating. “The crucial step toward improving your health is to be mindful of your fiber intake and gradually increase it,” he reassures. “Once you have made fiber consumption a habit, you can then be more particular about including more beta glucan and barley in your diet.” However, Duca cautions against processed foods that claim to be high in fiber. He cautions, “Many companies are under the impression that adding fiber to their products is sufficient, but often they include fiber that offers minimal benefits. It’s the type of fiber that passes through your system without triggering the release of any hormones.”
This compelling narrative was skillfully edited by Jane Greenhalgh.
