1
Appetite
GLP-1 signaling affects appetite-regulating areas of the brain, which can reduce hunger and food intake.
GLP-1s, Weight Loss & Nutrition
What GLP-1 medications do, what the research shows, and why nutrition still matters.
What Is GLP-1?
GLP-1 stands for glucagon-like peptide-1. It is a hormone naturally produced in the body, primarily in the intestine after eating.
GLP-1 plays several roles in metabolism. It helps stimulate insulin secretion when blood glucose is elevated, suppresses glucagon secretion, slows stomach emptying and influences appetite and food intake.
Medications that act on the GLP-1 pathway can therefore affect both blood sugar regulation and appetite.
Source: National Institute of Diabetes and Digestive and Kidney Diseases
GLP-1 FACT #1
~15%
Some GLP-1 medications can produce average weight losses in the range of 15% or more.
In the STEP 1 clinical trial, adults with overweight or obesity who received semaglutide 2.4 mg weekly along with lifestyle intervention experienced an average body-weight reduction of approximately 14.9% after 68 weeks.
Results vary substantially between individuals, and the medication used, dosage, duration of treatment and underlying health conditions all matter.
Research: New England Journal of Medicine
GLP-1 FACT #2
20.9%
Some participants in a major trial lost more than 20% of their starting body weight.
In the STEP 1 trial, approximately 32% of participants receiving semaglutide 2.4 mg achieved at least 20% weight loss after 68 weeks.
This illustrates an important point: average results do not tell the entire story. Some people experience considerably more weight loss than the average, while others experience less.
GLP-1 FACT #3
68 weeks
Significant weight loss develops over time, not overnight.
The major semaglutide STEP 1 trial followed participants for 68 weeks.
GLP-1 medications are not designed to produce instant results. Weight changes develop over months, while dosage is commonly increased gradually to improve tolerability.
This is one reason it is important to think about GLP-1 treatment as a longer-term health strategy rather than a short-term diet.
Research: New England Journal of Medicine
GLP-1 FACT #4
20%
Tirzepatide has produced average weight loss of around 20% in a major clinical trial.
Tirzepatide acts on both the GIP and GLP-1 receptors. In the SURMOUNT-1 trial, participants receiving the highest studied dose experienced an average weight reduction of approximately 20.9% after 72 weeks.
Tirzepatide is therefore technically a dual GIP/GLP-1 receptor agonist rather than a GLP-1-only medication.
GLP-1 FACT #5
~15%
GLP-1 medications can affect more than body weight.
GLP-1-based medications were originally developed primarily around glucose regulation and diabetes treatment.
Their effects on appetite, food intake, blood sugar, body weight and cardiovascular risk have made them an important area of modern metabolic medicine.
Some medications in this class have also demonstrated cardiovascular benefits in specific populations.
Source: U.S. Food & Drug Administration
HOW GLP-1s WORK
Why Do GLP-1 Medications Reduce Appetite?
GLP-1 receptor agonists affect several physiological processes involved in eating and digestion.
2
Stomach Emptying
GLP-1 medications can slow gastric emptying, meaning food may remain in the stomach longer.
3
Blood Sugar
GLP-1 receptor activation increases insulin secretion when glucose is elevated and suppresses glucagon.
4
Food Intake
Reduced appetite and increased satiety can result in lower overall food intake.
GLP-1 FACT #6
30%
Around 30% of participants in one major semaglutide trial experienced gastrointestinal side effects.
Gastrointestinal side effects are among the most common adverse effects reported with GLP-1 medications.
In the STEP 1 trial, gastrointestinal disorders occurred more frequently among participants receiving semaglutide than among those receiving placebo.
Common symptoms can include nausea, diarrhea, vomiting, constipation and abdominal discomfort.
Research: STEP 1 Trial
GLP-1 FACT #7
24%
Constipation affected nearly 1 in 4 participants receiving semaglutide in one major trial.
Constipation is one of the gastrointestinal effects reported with GLP-1 medications.
In the STEP 1 trial, constipation was reported by approximately 24.2% of participants receiving semaglutide, compared with approximately 11.1% receiving placebo.
Changes in appetite, food intake, digestion and hydration can all make digestive health especially important for people using GLP-1 medications.
Research: STEP 1 Trial
GLP-1 FACT #8
NUTRITION
Eating less makes nutrient density more important.
One of the defining effects of GLP-1 medications is reduced appetite. For some people, this can mean substantially smaller meals and fewer calories consumed throughout the day.
When total food intake decreases, it becomes increasingly important to make the food that is eaten count.
Protein, fiber, fruits, vegetables, whole grains and other nutrient-dense foods can help provide important nutrients without requiring large food volumes.
GLP-1 FACT #9
PROTEIN
Protein becomes particularly important when food intake decreases.
During weight loss, the body can lose both fat mass and lean mass. Adequate protein intake, combined with resistance exercise, is commonly recommended to help support lean tissue.
Protein needs vary depending on age, body size, activity level, health status and other factors.
Anyone using a GLP-1 medication who is struggling to eat enough should discuss their nutritional needs with a qualified healthcare professional or registered dietitian.
Research: Protein intake and preservation of lean mass during weight loss
GLP-1 FACT #10
FIBER
Fiber can be an important part of a GLP-1-friendly eating pattern.
Fiber contributes to digestive health, stool bulk and feelings of fullness. It is found naturally in foods including fruits, vegetables, legumes, nuts, seeds and whole grains.
Because constipation can occur with GLP-1 medications, maintaining adequate fiber and fluid intake may be particularly useful for some people.
However, rapidly increasing fiber can itself cause bloating or gastrointestinal discomfort. Increasing fiber gradually and drinking enough fluids is generally a better approach.
GLP-1 FACT #11
25–30g
Many adults fall short of recommended fiber intake.
The Dietary Guidelines for Americans and the National Academies provide age- and sex-specific fiber recommendations, with many adults needing roughly 25 to 38 grams per day.
Actual intake among Americans is generally much lower than recommended levels.
This matters for everyone, but digestive health may deserve additional attention when appetite and food intake change substantially.
Sources: Dietary Guidelines for Americans | National Academies
GLP-1 FACT #12
HYDRATION
Hydration becomes especially important when gastrointestinal symptoms are present.
Nausea, vomiting and diarrhea can increase the risk of fluid loss. Constipation can also be influenced by inadequate fluid intake.
There is no single amount of water that is right for everyone. Fluid needs vary based on body size, activity, climate, diet and health conditions.
People experiencing persistent vomiting, severe diarrhea or signs of dehydration should contact their healthcare provider.
Source: NIDDK
COMMON MISCONCEPTIONS
What GLP-1s Do — And Don't Do
✕ MYTH
"GLP-1s burn fat."
✓ FACT
GLP-1 medications primarily influence appetite, food intake, glucose regulation and digestion. Weight loss occurs largely because people consume fewer calories over time.
✕ MYTH
"You don't need to think about nutrition while taking a GLP-1."
✓ FACT
Reduced appetite can make it easier to eat less, but it can also make it harder for some people to consume enough protein, fiber, vitamins, minerals and fluids.
✕ MYTH
"Everyone loses the same amount of weight."
✓ FACT
Clinical trials report averages. Individual responses vary considerably.
✕ MYTH
"GLP-1s are a temporary diet."
✓ FACT
Obesity is considered a chronic disease, and some people require long-term treatment. Medication decisions should always be made with a healthcare professional.
✕ MYTH
"More weight loss is always better."
✓ FACT
Health outcomes involve much more than the number on a scale. Maintaining muscle, meeting nutritional needs, improving metabolic health and developing sustainable habits are also important.
✕ MYTH
"Side effects mean the medication isn't working."
✓ FACT
Side effects and effectiveness are separate issues. Anyone experiencing persistent or severe symptoms should discuss them with their healthcare provider.
AN IMPORTANT CONSIDERATION
What Happens When Someone Stops Taking a GLP-1?
One of the most important findings from GLP-1 research is that weight management does not necessarily end when the medication ends.
In the STEP 1 extension study, participants who stopped semaglutide after 68 weeks regained a substantial portion of the weight they had lost during the following year.
This does not mean that GLP-1 medications "don't work." Rather, it illustrates the chronic nature of weight regulation and why long-term treatment and lifestyle planning may be important for some individuals.
Research: Weight regain and cardiometabolic effects after withdrawal of semaglutide — PubMed
GLP-1 FACT #13
2/3
Participants regained roughly two-thirds of their previous weight loss after stopping semaglutide in one study.
One year after stopping semaglutide treatment, participants regained approximately two-thirds of their prior weight loss, on average.
This is one of the clearest demonstrations that weight-management treatment may need to be viewed as a long-term process rather than a short course with a guaranteed permanent endpoint.
Research: STEP 1 Extension Study
GLP-1 FACT #14
72 weeks
The largest weight-loss trials typically measure outcomes over many months, not weeks.
Major tirzepatide trials have followed participants for 72 weeks, while many semaglutide weight-loss trials have followed participants for 68 weeks or longer.
This is important when evaluating dramatic weight-loss claims online. A result measured over several months is very different from a claim about losing a large amount of weight in a few weeks.
THE GLP-1 NUTRITION CHECKLIST
Eating Less Doesn't Mean Eating Less Well
If appetite is significantly reduced, the goal should not simply be to eat as little as possible. The foods you do eat become increasingly important.
01
Prioritize Protein
Include protein-rich foods regularly to help meet nutritional needs and support lean mass during weight loss.
02
Get Enough Fiber
Fiber supports digestive health and can contribute to fullness. Increase intake gradually if your digestive system is sensitive.
03
Don't Forget Fluids
Adequate hydration is especially important when gastrointestinal symptoms occur.
04
Choose Nutrient-Dense Foods
When meals become smaller, foods containing useful amounts of protein, fiber, vitamins and minerals can help make each meal more nutritionally valuable.
05
Eat Slowly
Because GLP-1 medications can slow gastric emptying, eating slowly and paying attention to fullness may help reduce discomfort.
06
Keep Moving
Regular activity, particularly resistance exercise, can complement nutritional strategies during weight loss.
NUTRITION FOR THE GLP-1 LIFESTYLE
When You Eat Less, Make What You Eat Count.
GLP-1 medications can change how much and how often you want to eat. That makes food quality even more important.
HAC creates chocolate-based foods designed with meaningful amounts of fiber and protein, giving you another option when you're looking for something satisfying without completely abandoning the foods you enjoy.
THE RESEARCH
GLP-1 Research Library
The information on this page is based on clinical trials, government health agencies and peer-reviewed medical research.
Semaglutide and Weight Loss
The STEP 1 randomized clinical trial examining once-weekly semaglutide for weight management.
View the NEJM study →Tirzepatide and Weight Loss
The SURMOUNT-1 clinical trial examining tirzepatide in adults with obesity or overweight.
View the NEJM study →Weight Regain After Stopping Semaglutide
Follow-up research examining what happened after participants stopped semaglutide treatment.
View the PubMed research →FDA: Wegovy
FDA information regarding the approval and indications for Wegovy (semaglutide).
View FDA information →NIDDK: GLP-1 Medicines
Government information about medications used to treat diabetes and their effects on glucose regulation.
Read NIDDK information →NIDDK: Fiber & Constipation
Information about dietary fiber, fluids and dietary approaches that can help support regular bowel movements.
Read NIDDK guidance →This page is intended for general educational and informational purposes only. It is not medical advice and is not intended to diagnose, treat, cure or prevent any disease or medical condition.
GLP-1 and GLP-1-based medications are prescription medications that should only be used under the direction and supervision of a qualified healthcare professional. Medication effects, side effects, contraindications and appropriate dosages vary by medication and by individual. Never start, stop, change or combine prescription medications without discussing the decision with your healthcare provider. If you experience severe or persistent abdominal pain, repeated vomiting, signs of dehydration or other concerning symptoms while taking a GLP-1 medication, contact your healthcare provider.
HAC products are foods and are not medications. HAC products do not contain GLP-1 medications and are not intended to produce the effects of GLP-1 prescription drugs. HAC products support GLP-1 diets due it's high fiber and other optimal ingredients.