Weight loss is one of those things everybody talks about. But first of all, losing weight and losing fat are not exactly the same thing. And now peptides are everywhere. So what should you actually look at?
The scale is only part of it [4]
Weight loss
The scale goes down.
- Fat
- Muscle
- Water
- Other tissues
Fat loss
Body fat goes down.
A peptide is a chain of amino acids.
Simple illustration, not a drug’s actual structure.
These medicines activate different hormone receptors. Think of a receptor as a place where a signal is received.
Single target
Semaglutide
Liraglutide
Dual target
Tirzepatide
Triple target
Retatrutide
Investigational. Not FDA-approved.
Names you may have heard [1][3]
Selected U.S. weight-management brands, as of October 2, 2026. Approval is for the listed prescription brand, not every product with the same ingredient.
| Peptide | U.S. status |
|---|---|
| Tirzepatide Zepbound | FDA-approved prescription |
| Semaglutide Wegovy | FDA-approved prescription |
| Liraglutide Saxenda | FDA-approved prescription |
| Retatrutide | Not FDA-approved |
How do they help? [5]
For semaglutide and tirzepatide, the main effects include:
- Appetite
- Less hunger and lower calorie intake.
- Stomach
- Food leaves the stomach more slowly.
- Blood sugar
- More insulin is released when blood sugar is high.
Which worked better in a trial? [2]
Average body-weight reduction at 72 weeks
SURMOUNT-5: 751 adults with obesity, without diabetes. Weekly injections: tirzepatide 10 or 15 mg versus semaglutide 1.7 or 2.4 mg, at maximum tolerated doses. Diet and activity support in both groups. Lilly-funded study.
Trial doses, not instructions. This did not compare every formulation or dose available in 2026.
So is tirzepatide the best? It led that comparison. But the right medicine depends on your health, side effects and cost. A bigger number does not automatically make it right for you. [1][2]
Before comparing brands, ask these.
- Am I a suitable candidate, given my health and weight-related conditions?
- What follow-ups, side effects and costs should I plan for?
- What is the long-term plan if treatment works, or if I need to stop?
Treatment may be long-term. Weight can return after stopping; plan this with your prescriber rather than treating it as a short course. [1]
Was all the lost weight fat? [6]
Share of weight lost with tirzepatide in a separate 72-week study
lostnot body-fat %
- 74% fat mass
- The larger share.
- 26% lean mass
- Not all muscle. Lean tissue also includes water and organs.
SURMOUNT-1 DXA substudy: 160 people; 124 received tirzepatide. The placebo group had a similar split, 75% fat and 25% lean mass, but less total weight loss. Lilly-funded.
The food part still matters. If you feel less hungry, it is easy to eat less without thinking about what is missing. The aim is not to see how little you can eat. [4]
On a busy evening, use our cook, freezer and no-cook meal backups for ideas. Adjust portions and ingredients with your care team if eating is difficult.
What can you eat alongside treatment? [7]
No special “peptide food.” Start with a balanced meal.
Vegetables
& fruit¼
Protein¼
Whole
grains
- Vegetables & fruit
- Spinach, carrots, berries, apples.
- Protein foods
- Eggs, yogurt, tofu, lentils, fish, chicken.
- Whole grains
- Oats, brown rice, whole-grain bread.
Adapted from Canada’s food guide. A meal-building guide, not a calorie or protein prescription. Portions depend on your needs and tolerance.
Feed it
Include protein regularly. Ask for a personal target, especially with kidney disease.
Use it
Strength training: weights, bands or body-weight exercises, adapted to your ability.
Check it
Track strength. Tell your clinician if you feel weaker or cannot eat enough.
General adult minimum for muscle-strengthening activity. Keep regular aerobic activity too. Your clinician may recommend more.
| What is happening? | What to do |
|---|---|
| Mild nausea or early fullness | Try smaller meals. Large, fatty meals may make symptoms worse. |
| Constipation | Fluids and fiber may help. Increase fiber as tolerated; ask if it persists. |
| Severe, ongoing belly pain or unable to keep fluids down | Get medical help urgently. Do not just wait for it to pass. |
- WeightThe trend
- WaistChange over time
- StrengthDaily ability
- NutritionEnough food
Waist and strength are useful checks, not exact measurements of fat or muscle. Discuss concerns at follow-ups.
One important thing: these are prescription treatments, not for everyone. Tell your clinician about pregnancy and your medical history. The approved medicines listed here must not be used with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2 (MEN2), a rare inherited condition. Avoid “research-only” sellers. General information, not a prescription. [3][5]
Bring the details to your care team.
- Your medicine list: especially insulin or sulfonylureas, because low blood sugar may need extra attention.
- Upcoming procedures: tell the team before anesthesia or deep sedation that you use a GLP-1 medicine.
- Oral birth control with tirzepatide: ask about a non-oral method or an added barrier method for four weeks after starting and for four weeks after each dose increase, as its label recommends.
Do not adjust medicines on your own. These checks come from the Zepbound prescribing information. [5]