Is there one best diet while taking semaglutide or tirzepatide?

No single diet—keto, paleo, low-fat, or carnivore—has been proven superior for GLP-1 therapy. Research shows that when calories and adherence are equal, most diets produce similar weight loss. The best diet is one that supports a sustainable calorie deficit while protecting health, muscle mass, and quality of life.

What kind of diet was used in the STEP and SURMOUNT trials?

In the STEP-1 and SURMOUNT-1 trials, participants followed a reduced-calorie diet targeting approximately a 500 kcal/day deficit and engaged in at least 150 minutes per week of moderate-intensity physical activity, typically brisk walking. There was no requirement for keto, fasting, very low-carb, or other extreme diets.

What role does protein play while on GLP-1 medications?

GLP-1 medications can significantly reduce appetite, which may lead to low protein intake. Higher protein intake, in the range of about 1.2–1.6 g/kg/day, helps preserve lean muscle while losing fat, especially when combined with resistance training. Examples include Greek yogurt, eggs, lean meats, tofu, and beans.

How much fiber should I aim for on semaglutide or tirzepatide?

Most adults should aim for roughly 25–38 g of fiber per day from foods such as vegetables, fruits, whole grains, legumes, nuts, and seeds. Adequate fiber supports gut motility, fullness, blood sugar control, and cardiovascular health. Increase fiber gradually and drink enough fluids to reduce GI discomfort.

Which diet best supports heart health while on GLP-1 therapy?

The Mediterranean diet has the strongest evidence for long-term cardiovascular benefit. It emphasizes vegetables, fruits, whole grains, legumes, olive oil, and lean proteins, with limited refined grains, added sugars, and processed meats. This diet reduces the risk of heart attack, stroke, and cardiovascular death and complements GLP-1 therapy.

Can GLP-1 therapy increase the risk of nutrient deficiencies?

Because GLP-1 medications reduce appetite and overall intake, some patients may consume fewer vitamins and minerals. Real-world data show increased rates of nutritional deficiencies, especially vitamin D, in the first year of GLP-1 therapy. A high-quality, nutrient-dense diet, a basic multivitamin, and periodic lab monitoring when appropriate can help prevent these issues.

The Best Diet for Semaglutide and Tirzepatide: Evidence-Based Nutrition for GLP-1/GIP Weight Loss

Joshua Silva, MD
Jan 13
6 min read

Updated: Jan 15

Medically authored by Joshua Silva, MD | Evidence-Based Weight Loss at Potere Health MD

Last clinically updated: January 2026

When patients start semaglutide (a GLP-1) or tirzepatide (a GLP-1/GIP), one of the first questions they ask is:

“What diet should I follow to get the best results?”

The truth: there is no single “perfect” diet for GLP-1 medications.

But research is extremely clear about what does work — and the common patterns behind every successful, sustainable approach to weight loss.

This post walks through what the research actually shows — and how to use it in real life.

“Healthy whole foods for an optimal semaglutide (GLP-1) and tirzepatide (GIP) diet, including vegetables, lean protein, healthy fats, whole grains, nuts, seeds, and high-fiber foods.”

Is There One Optimal Diet While Taking Semaglutide or Tirzepatide? What the Evidence Shows

Clinical research doesn’t support one specific diet — not keto, not paleo, not low-fat, not carnivore — as the superior option for GLP-1 therapy. In large comparative studies, most diets produce similar weight loss when total calories and adherence are equal (JAMA, 2014; BJM, 2020).

So the question isn’t “keto vs paleo vs intermediate fasting.”

It’s: “What way of eating helps you stay in a sustainable calorie deficit while protecting your health, muscle, and quality of life?”

GLP-1 medications make this easier by reducing hunger, cravings, and portion sizes — but the underlying nutrition principles stay the same.

What All Successful Weight-Loss Diets Have in Common (With or Without GLP-1/GIP Medications)

1. A consistent calorie deficit

Every effective weight-loss diet — low-carb, low-fat, Mediterranean, whole-food, plant-based — works through the same mechanism: you eat fewer calories than you burn.

Most structured healthcare professionals and dieticians recommned about a 500-calorie-per-day reduction, which usually produces ~1-2 lb/week weight loss early on (slowing over time as metabolism adapts).

The STEP-1 semaglutide trial and the SURMOUNT-1 tirzepatide trial both used this approach: participants were counseled to follow a reduced-calorie diet with ~500 kcal/day deficit plus increased physical activity (≥150 minutes/week of moderate exercise, usually walking).

2. Not extreme or overly restrictive

Highly restrictive diets (very low carb, very low calorie, extreme fasting) can cause quick results — but nearly always fail long-term.

Long-term data show only ~20–25% of people maintain significant weight loss with traditional dieting alone (Am J Clin Nutr, 2005; Nutrients, 2022).

The problem isn’t willpower. It’s that extreme diets are not sustainable lifestyles. Once the diet phase ends, people slide back to old eating patterns – and their weight follows.

Why Most Diets Fail Long-Term — and How GLP-1/GIPs Fit Into Sustainable Weight Loss

Patients often ask:

“How long do I have to be on this medication?”

This assumes weight loss is a temporary project — like doing something difficult for a few months, then returning to old habits.

If you revert to old behaviors, your body reverts to your old weight.

That’s true after diets, after medications, and even after many bariatric surgeries if habits revert.

GLP-1s like semaglutide and tirzepatide can be:

· A short-to-medium-term tool to help you build new habits, or

· A long-term medical treatment in a chronic disease (obesity) for some people.

Either way, the lifestyle has to be durable.

How to Approach Nutrition on GLP-1s: Shift From Short-Term “Dieting” to Long-Term Lifestyle

Instead of extreme diets, aim for small, sustainable habits you can imagine doing longterm:

Making most meals a good balance of lean protein + vegetables + high-fiber carb + healthy fat.
Choosing whole foods over ultra-processed snack foods
Drinking more water and fewer sugary drinks
Eating slowly and stopping before you feel stuffed
Walking most days of the week

GLP-1s create a window where appetite is reduced — use that period to practice the lifestyle you want to keep.

What Diet Did the STEP and SURMOUNT Trials Use With Semaglutide and Tirzepatide?

This question matters — because these trials produced some of the most effective non-surgical weight-loss results ever recorded.

Here’s what participants actually did:

A reduced-calorie diet targeting ~500 kcal/day deficit
Balanced macronutrient intake (no strict macro rules — just reasonable, mixed meals)
At least 150 minutes per week of physical activity (usually brisk walking)

Important:There was no keto requirement, no fasting protocol, no low-carb mandate, no high-protein rule.

(STEP-1: NEJM, 2021; SURMOUNT-1: NEJM, 2022)

How to Choose a Diet That Supports Heart Health While on GLP-1/GIP Therapy

Weight loss is only one goal. Health is the bigger goal.

The diet with the strongest evidence for long-term cardiovascular benefits is the Mediterranean diet (PREDIMED Trial — NEJM, 2013):

High in vegetables, fruits, whole grains, legumes
Olive oil as primary fat source
Lean proteins (fish, poultry, plant-based)
Limited refined grains, added sugars, and processed meats

This diet reduces:

Heart attack risk
Stroke risk
Cardiovascular mortality

It pairs extremely well with the metabolic benefits of GLP-1 medications.

Essential Nutrition Principles for Patients Using Semaglutide or Tirzepatide

1. Prioritize Protein to Preserve Lean Muscle During GLP-1 Weight Loss

GLP-1 medications reduce appetite so effectively that patients may accidentally undereat protein.

Research shows higher protein intake preserves more lean mass.

Target: 0.5–1 g/lb/day (roughly 25–35 g per meal).(Adv Nutr, 2022)

Great options:

Greek yogurt
Chicken/turkey/fish
Eggs
Beans/lentils
Tofu and tempeh
Protein shakes when appetite is low

2. Increase Dietary Fiber to Improve Gut Health and Satiety While on GLP-1s

Aim for 25–38 g/day (Academy of Nutrition & Dietetics, 2015).

Fiber helps:

Gut motility
Fullness
Blood sugar stability
Cardiovascular health

Start slow if you’re sensitive, and drink plenty of fluids.

3. Choose Healthy Fats and Avoid Greasy, Heavy Meals That Trigger GLP-1 Side Effects

High-fat, greasy meals tend to worsen nausea and reflux on semaglutide or tirzepatide because they stay in the stomach longer.

Avoid:

Deep-fried foods
Fast-food burgers/fries
Heavy cream-based meals

Choose:

Olive oil
Nuts and seeds
Avocado
Salmon, sardines, trout

4. Maintain Adequate Micronutrients: Don’t Let Appetite Suppression Create Gaps

Because GLP-1s reduce overall intake, patients may unintentionally cut back on key nutrients.

Studies show higher rates of deficiencies—especially vitamin D—within the first year of therapy. A multi-society advisory also confirms that reduced intake can create nutritional gaps, making diet quality essential. (Obesity Pillars, 2025, Am J Clin Nutr/Obesity Pillars, 2025)

Nutrient deficiencies are also an avoidable contributor to hair shedding and other weight-loss side effects.

Helpful steps:

Eat a variety of whole foods
Consider a simple daily multivitamin
Ask your clinician if lab monitoring is appropriate

The Ideal Diet on Semaglutide or Tirzepatide: A Practical, Evidence-Based Framework

The most effective and sustainable approach includes:

✔ A modest calorie deficit (~500/day)

✔ 0.5-1 g/lb/day of protein

✔ 25–35 g/day of fiber

✔ Mediterranean-style eating pattern if cardiovascular health is valued

✔ Limited ultra-processed foods and greasy/fried meals

✔ Plenty of water and slower eating habits

✔ Regular physical activity + resistance training

No fads.

No extremes.

Just a healthy, balanced, science-backed way of eating that aligns with the most successful GLP-1 trials to date — and supports your long-term health.

Disclaimer:

This article is for educational purposes only and is not a substitute for medical advice.

About the Author

Dr. Joshua Silva, MD, is a licensed physician and Medical Director of Potere Health MD. He earned his medical degree from the University of Hawaiʻi John A. Burns School of Medicine and completed residency training in Occupational and Environmental Medicine at the University of Utah, where he also earned a master’s degree in Occupational Health. He later completed a Master of Business Administration with an emphasis in health care administration at Ohio University.

Dr. Silva specializes in evidence-based weight management, including GLP-1 and GIP therapies such as semaglutide and tirzepatide. He provides in-person and virtual care for patients in Salt Lake City, St. George, and Cedar City, Utah.

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