Bariatric Surgery Calorie Calculator

Calculate your recommended daily calorie intake after bariatric surgery based on your personal information and surgery type.

Age Your current age in years

Gender

Height Your height in centimeters

Current Weight Your current weight in kilograms

Activity Level

Bariatric Surgery Type

Months Since Surgery: 6 How many months have passed since your surgery?

I want to continue losing weight

Quick Examples:

How to Use This Calculator

Enter your personal information (age, gender, height, and current weight)
Select your typical activity level
Choose the type of bariatric surgery you had or are considering
Adjust the slider to indicate how many months have passed since your surgery
Check the box if you want to continue losing weight
Click Calculate to see your recommended daily calorie intake

Formula Used

BMR (Mifflin-St Jeor Equation):
Male: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
Female: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

TDEE = BMR × Activity Factor
Recommended Calories = TDEE × Surgery Adjustment Factor

Where:

BMR = Basal Metabolic Rate (calories burned at rest)
TDEE = Total Daily Energy Expenditure
Surgery Adjustment Factor = Varies by surgery type and time since surgery

Example Calculation

Real-World Scenario:

Sarah is a 35-year-old female who had gastric bypass surgery 6 months ago. She is 165 cm tall, weighs 85 kg, and has a moderately active lifestyle.

Given:

Age = 35 years
Gender = Female
Height = 165 cm
Weight = 85 kg
Activity Level = Moderately active (1.55)
Surgery Type = Gastric Bypass
Months Since Surgery = 6

Calculation:

BMR = (10 × 85) + (6.25 × 165) - (5 × 35) - 161 = 1,564 calories

TDEE = 1,564 × 1.55 = 2,424 calories

Recommended Calories = 2,424 × 0.65 (adjustment factor for 6 months post-gastric bypass) = 1,576 calories

Result: Sarah should consume approximately 1,576 calories per day, with at least 60-80 grams of protein.

Why This Calculation Matters

Practical Applications

Preventing nutritional deficiencies after surgery
Supporting healthy weight loss or maintenance
Ensuring adequate protein intake for muscle preservation

Key Benefits

Personalized nutrition recommendations based on surgery type
Adjusts for different phases of post-surgery recovery
Helps optimize long-term weight management success

Common Mistakes & Tips

After bariatric surgery, protein needs increase significantly (typically 60-80 grams per day). Focus on protein-rich foods first at each meal to ensure you're meeting your requirements. Consider protein supplements if needed.

Your calorie needs will change as you lose weight and as you progress further from your surgery date. Recalculate your needs every 3-6 months or whenever you experience significant weight changes.

Frequently Asked Questions

Different bariatric procedures affect digestion and absorption differently. Gastric bypass typically requires the most restrictive calorie intake (especially in the first year), while gastric band surgery generally allows for higher calorie intake. Sleeve gastrectomy falls between these two, and duodenal switch requires the most careful nutritional monitoring due to malabsorption.

Calorie intake typically increases gradually after surgery. Most patients start with 600-800 calories per day for the first 3 months, then increase to 800-1000 calories until 6 months post-op. After 6 months, intake may increase to 1000-1200 calories, and eventually to 1200-1500 calories for maintenance. However, these are general guidelines and individual needs vary.

Yes, lifelong supplementation is essential after bariatric surgery. Most patients need a multivitamin, calcium with vitamin D, iron, and vitamin B12. Some procedures, particularly malabsorptive ones, may require additional supplements like vitamin A, D, E, K, and zinc. Always follow your surgeon and dietitian's specific recommendations.

References & Disclaimer

Medical Disclaimer

This calculator provides general nutritional guidelines for bariatric surgery patients and is not a substitute for professional medical advice. Always consult with your healthcare team, including your surgeon and registered dietitian, for personalized nutrition recommendations based on your specific health status and surgical procedure.

References

American Society for Metabolic and Bariatric Surgery: After Bariatric Surgery Diet and Nutrition - Comprehensive nutritional guidelines for post-bariatric surgery patients
National Institute of Diabetes and Digestive and Kidney Diseases: Life After Bariatric Surgery - Information about diet and lifestyle changes after surgery
American Society for Metabolic and Bariatric Surgery: Bariatric Surgery Background Information - Clinical practice guidelines for bariatric surgery

Accuracy Notice

This calculator provides estimates based on established formulas and clinical guidelines for bariatric nutrition. Individual calorie needs may vary based on medical conditions, medications, and other factors. The calculator is most accurate for adults between 18-80 years of age who have had or are considering standard bariatric procedures.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

Connect with LinkedIn

Tags:

health medical-clinical-calculators bariatric surgery calorie medical body weight

Related Calculators