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GLP-1 is a hormone made in your gut. It is one reason a plate of rajma-chawal keeps you going until evening while a glass of mango juice with the same calories is forgotten by eleven. The letters stand for glucagon-like peptide-1. Cells in the lower small intestine and colon release it as a meal reaches them, and a few nerve cells in the brainstem make it as well. For the next hour or so it raises insulin while sugar climbs, holds back glucagon, keeps food in the stomach longer and feeds the sense of having eaten enough. Each molecule works only briefly, since an enzyme called DPP-4 breaks it down within a couple of minutes.
GLP-1 is a peptide hormone of about 30 amino acids, not an enzyme. Food does not contain it; meals prompt your gut to make its own. Protein, fibre and eating vegetables before rice or roti all raise how much your body releases.
What is the GLP-1 hormone, and where is it made?
The gut is the body's largest hormone-making organ. Scattered among the cells that absorb food are millions of sensor cells that taste what passes and answer with hormones. L-cells are one type. They are thickest in the last stretch of the small intestine, the ileum, and in the colon.
L-cells read a gene called proglucagon. The pancreas uses the same gene to make glucagon, the hormone that pushes blood sugar up between meals. L-cells cut the long protein at different points, and one of the fragments is GLP-1. Jens Juul Holst of the University of Copenhagen, who has studied it since the 1980s, describes it as a 30-amino-acid peptide hormone. A peptide is simply a short chain of amino acids, shorter than a protein.
Some nerve cells in the brainstem carry the same gene and make their own GLP-1, which they send to brain areas that govern appetite. The gut version and the brain version are the same molecule doing related jobs, one after each meal and one as part of the brain's standing control of hunger.
Sources: [1]
Is GLP-1 a hormone or an enzyme?
A hormone. The mix-up usually comes from DPP-4, short for dipeptidyl peptidase-4, the enzyme that switches GLP-1 off. DPP-4 lines the small blood vessels of the gut and floats in the blood. It snips two amino acids off the front of GLP-1, and the clipped version barely acts on the GLP-1 receptor.
It works fast enough that most of the GLP-1 made after a meal is inactivated before it reaches the main bloodstream. Holst's review raises the possibility that much of the hormone's effect travels along nerves in the gut wall and liver, rather than through the blood alone. Many readers will know the name from a family of tablets that block it, letting natural GLP-1 last a little longer.
The speed also explains why no routine lab in your city lists a GLP-1 test. Researchers who measure it add a DPP-4 blocker to the tube the moment blood is drawn and keep samples on ice. They still have to choose between counting only the intact hormone or everything the L-cells released.
Sources: [1]
What does GLP-1 do after you eat?
Its best-known job is as an incretin, a gut hormone that boosts insulin release after food. The boost only happens when blood sugar is rising, which is why GLP-1 on its own does not push sugar too low. At the same time it holds back glucagon, so the liver releases less stored sugar while a meal is being absorbed.
It also acts as a brake on the gut. Food leaves the stomach more slowly, the small intestine slows down, and the rise in blood sugar after a meal is flatter. Researchers call this the ileal brake. It is part of why a meal with dal and sabzi keeps you full longer than the same calories as a glass of juice.
GLP-1 also acts on appetite directly. A pooled analysis from Copenhagen combined data from 115 volunteers who were given GLP-1 by drip or salt water before a free buffet. With GLP-1 they ate about 12% less, roughly 170 calories, and the effect held for lean and overweight volunteers alike. Their stomachs emptied more slowly, and they reported feeling fuller.
Why does GLP-1 seem to work less well in diabetes and obesity?
In healthy adults, gut hormones account for a large share of the insulin released after eating. Nauck's group in Göttingen measured this in 1986 by giving the same rise in blood sugar twice, once as a sugary drink and once through a drip. In healthy volunteers, gut factors explained about 73% of the insulin response to the drink. In adults with type 2 diabetes the figure was about 36%. This loss of the incretin effect is one of the defining features of the condition.
Lower GLP-1 output may also be part of the picture in obesity. In a small study from the University of Surrey, six women living with obesity released much less GLP-1 after a carbohydrate meal than six lean women of the same age. Their response to a fatty meal was similar. The authors could not tell whether the low response was a cause of weight gain or a result of it, and the samples were small. Later research has been mixed.
In India, type 2 diabetes and insulin resistance often appear at a lower body weight than in Western populations. A body that releases less GLP-1, or responds to it less, gets a weaker fullness signal and a bigger sugar spike from the same plate of rice.
Which foods raise GLP-1 naturally?
No food contains GLP-1. Food triggers your own L-cells to release it, and some foods do that better than others.
Protein is the most reliable. A 2023 review of 16 crossover trials found that a small serving of whey protein taken shortly before a meal lowered the peak in blood sugar, raised insulin and slowed stomach emptying. GLP-1 rose too, though the evidence on that point was rated low certainty. You do not need a powder to use the idea. A bowl of curd, a glass of chaas with roasted chana, two eggs or a handful of paneer cubes at the start of a meal brings protein in early.
Fibre works more slowly, through your gut bacteria. When bacteria in the colon ferment fibre, they make short-chain fatty acids such as propionate, which prompt L-cells to release GLP-1 and its sister hormone PYY. At Imperial College London, Edward Chambers's team gave 60 overweight adults a fibre-bound propionate supplement for 24 weeks. Those taking it gained less weight and less abdominal fat than a fibre-only control group. In everyday food, the fermentable fibre comes from whole dals, rajma, chana, oats, barley, onions, green bananas and cooked-then-cooled rice or potatoes.
Does the order you eat food in change GLP-1?
It can. In a Singapore trial, 16 healthy adults ate one meal of vegetables, chicken breast and white rice on five separate mornings, each time in a different order. Vegetables first, then chicken, then rice gave the highest GLP-1 release and a far flatter sugar curve than rice eaten first.
Alpana Shukla's team at Weill Cornell in New York tried it in 16 adults with type 2 diabetes. When the carbohydrate came 10 minutes after the protein and vegetables, the rise in blood sugar was about half as large as when it came first. GLP-1 was higher, and the pancreas needed less insulin.
At an Indian thali, start with the kachumber or a katori of sabzi. Move on to the dal, curd, egg or chicken, and keep the rice or roti for the last part of the meal. Both trials were small and short, so think of this as a habit that tilts each meal in your favour rather than a treatment.
Do exercise and dieting change your GLP-1?
Exercise gives it a modest push. Researchers at Griffith University in Australia pooled 20 studies that tracked appetite hormones through a single workout and the hours after it. GLP-1 rose by a median of about 13%, although with so few studies the result fell short of statistical certainty. PYY, another fullness hormone, rose too, and ghrelin, which drives hunger, fell.
Crash dieting is a different matter. Joseph Proietto's group at the University of Melbourne put 50 adults on a ten-week very low calorie diet and checked their appetite hormones a year later. Leptin, PYY and CCK were still below where they started, ghrelin was still higher, and the volunteers still felt hungrier. GLP-1 was not among the hormones that had shifted significantly, but the rest of the system was leaning hard towards regain.
That is the argument for losing slowly, eating enough protein and staying active while you do it, so the hunger signals have less to push back against.
How do GLP-1 medicines differ from the hormone your body makes?
Your own GLP-1 lasts a couple of minutes. The medicines modelled on it were redesigned so that DPP-4 cannot cut them, and the longest-acting kind is given once a week. They keep the GLP-1 receptor switched on day and night, at levels a meal never reaches. A thali eaten in the right order helps your natural hormone; it does not turn into a treatment. Nausea, early fullness and constipation are the usual complaints in the first weeks, which is why doctors start low and step up slowly.
There is also the question of muscle. Ian Neeland's 2024 review gathered body-scan data from trials of GLP-1-based therapies and found a wide spread. In some trials, lean tissue was 40–60% of everything lost; in others it was 15% or less. Lean mass includes water and organs, so true muscle loss is smaller, but protein and strength work are what keep it small.
At Metaboliq the starting point is a home blood test, with a doctor going through sugar, insulin, lipids and thyroid with you. Any treatment is the doctor's call, and many plans use none. Protein and two strength sessions a week are built in from the start, because the aim is to lose up to 20% of body weight while you keep your muscle.
Sources: [9]