What foods are allowed on a PSMF diet?

December 20, 2025 •

3 min read

According to Healthline, a protein-sparing modified fast (PSMF) is a highly restrictive diet primarily consisting of lean protein and non-starchy vegetables. This guide details what foods are allowed on a PSMF diet to help you navigate this short-term, medically-supervised weight loss plan.

Quick Summary

The Protein Sparing Modified Fast (PSMF) focuses on high-protein foods and specific non-starchy vegetables to induce ketosis for rapid fat loss. Learn about approved lean proteins, limited vegetables, and essential supplements while avoiding fats, sugars, and starchy carbohydrates.

Key Points

Core Foods: Lean proteins like skinless chicken breast, white fish, and egg whites are the foundation of the PSMF diet.
Vegetable Limit: Only low-carb, non-starchy vegetables such as leafy greens, broccoli, and cauliflower are permitted.
No Fats or Sugars: All added fats, sugars, fruits, grains, and most dairy products are strictly forbidden.
Short-Term Plan: PSMF is designed for short-term use and requires medical supervision due to its restrictive nature.
Supplementation is Necessary: Because of its limited food options, hydration and supplementing with multivitamins and electrolytes are crucial.
Differs from Keto: Unlike a traditional ketogenic diet, PSMF is very low in fat, with protein providing the majority of calories.
Avoid Processed Foods: Processed meals and snacks, including packaged junk foods, must be eliminated entirely.

The Protein Sparing Modified Fast (PSMF) is a very low-calorie, high-protein diet designed to promote rapid fat loss while preserving lean muscle mass. By severely limiting carbohydrates and fats, the body is forced into a state of ketosis, where it burns stored body fat for fuel. The diet is extremely restrictive and should only be undertaken for short periods under medical supervision. To follow it correctly, it is crucial to know precisely what foods are allowed on a PSMF diet and which must be strictly avoided.

The Core of PSMF: Protein is King

The central pillar of the PSMF is a high intake of lean, high-biological-value protein. This high protein consumption is what "spares" your muscle tissue from being broken down for energy. Protein is also highly satiating, which helps manage hunger during a very low-calorie intake. Your daily protein target is typically calculated based on your ideal body weight.

PSMF Protein Sources

Poultry: Skinless chicken and turkey breast.
Seafood: White fish like cod, halibut, and sole, plus shellfish like shrimp.
Lean Meats: Very lean cuts of beef, pork, and lamb.
Eggs: Primarily egg whites, but some plans may allow limited whole eggs.
Low-Fat Dairy: Fat-free cottage cheese, skim milk, and some low-fat cheeses.
Tofu: A plant-based, lean protein option.

The Role of Non-Starchy Vegetables

To provide essential fiber, vitamins, and minerals, a limited amount of non-starchy vegetables is permitted. These vegetables are very low in carbohydrates and calories, making them a safe choice to fill out meals without derailing ketosis. They also add valuable volume and variety to an otherwise very simple diet.

Non-Starchy Vegetables List

Leafy greens (spinach, lettuce, kale)
Broccoli and cauliflower
Asparagus and Brussels sprouts
Cucumber and celery
Mushrooms, onions, and tomatoes
Bell peppers

Strict No-Go Zones: Foods to Avoid

A key aspect of the PSMF is the near-total elimination of fats and carbohydrates. This includes a wide range of foods that are common in a typical diet. Adherence to these restrictions is non-negotiable for the diet to be effective.

Prohibited Foods on PSMF

Fruits: All fruits are generally forbidden due to their sugar content.
Starchy Vegetables: Potatoes, corn, and peas are off-limits.
Grains and Legumes: Breads, pasta, rice, beans, and lentils are not allowed.
Fats and Oils: Added fats like olive oil, butter, and salad dressings are prohibited.
Sugars and Sweeteners: This includes honey, maple syrup, and any sugar-sweetened beverages.
Processed Foods: Convenience meals, baked goods, and fast food are forbidden.

PSMF vs. Traditional Ketogenic Diet

While both PSMF and a traditional ketogenic diet induce ketosis, their macronutrient profiles are fundamentally different. This distinction is crucial for understanding what foods are allowed on a PSMF diet compared to keto.


Feature	PSMF Diet	Traditional Ketogenic Diet
Primary Calorie Source	Lean Protein	Fat
Fat Intake	Very Minimal (near zero)	High (60-75% of calories)
Carb Intake	Extremely Low (typically <20g/day)	Low (typically <50g/day)
Primary Goal	Rapid Fat Loss	Stable Ketosis for various goals
Duration	Short-term (under medical supervision)	Long-term (can be sustained indefinitely)

Crucial Hydration and Supplementation

Due to the highly restrictive nature of the PSMF diet, nutritional deficiencies are a major concern. It is essential to drink 1-2 liters of water daily to stay hydrated. Additionally, supplementation with a multivitamin, along with electrolytes like sodium, potassium, calcium, and magnesium, is often necessary to prevent serious health issues. Proper hydration also helps mitigate issues like constipation.

Conclusion: Short-Term Strategy for Fat Loss

In summary, the PSMF is an effective but highly restrictive method for rapid fat loss under medical supervision. The diet's strict rules mean that what foods are allowed on a PSMF diet are limited to lean proteins and non-starchy vegetables, while most other food groups are forbidden. Following the diet plan, staying hydrated, and taking necessary supplements are critical for safely achieving results. The intensive phase is followed by a refeeding phase where fats and carbohydrates are slowly reintroduced to maintain weight loss.

For more detailed information, consult authoritative medical resources like this guide from the Cleveland Clinic: What to Know About the Protein-Sparing Modified Fast Diet.

Frequently Asked Questions

No, all fruits are typically forbidden on a PSMF diet due to their high sugar content, which can interfere with the metabolic state of ketosis.

No, grains and legumes, including bread, pasta, and beans, are not allowed because they are high in carbohydrates, which are strictly limited on this diet.

Added fats and oils, such as olive oil, butter, and salad dressings, are generally prohibited during the intensive phase of the PSMF to keep calories very low.

Yes, due to the diet's restrictive nature, supplementation with multivitamins and electrolytes like potassium, sodium, calcium, and magnesium is often recommended under medical supervision.

No, full-fat dairy products like milk, cheese, and yogurt are avoided. However, low-fat options such as skim milk or fat-free cottage cheese may be included in moderation.

The main difference is the macronutrient ratio. A PSMF focuses on high protein and very little fat, whereas a traditional keto diet is high in fat and moderate in protein.

No, the PSMF diet is a short-term, medically supervised program for rapid weight loss. It is followed by a refeeding phase to slowly reintroduce more foods.