Bariatric surgery is a life-saving procedure through which you will lose weight, reduce your co-morbidities and look and feel better. But to be successful long term, you will have to change your diet. It sounds easy enough – but is it? Change is difficult, especially for people who have spent much of their lives without a healthy relationship with food. Having goals and a plan in place is essential to managing this change.
Key takeaways
- There is no validated equation for calorie needs after bariatric surgery – focus on food quality over quantity.
- Typical ranges: about 400 kcal/day in week 1, 600–800 kcal/day by weeks 3–4, and 1,500–1,800 kcal/day from 6 months.
- Aim for 60–80 grams of protein per day.
- Eat protein first, eat slowly and eat small amounts.
How surgery changes your intake
Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) and biliopancreatic diversion with duodenal switch (BPD/DS) alter how the stomach handles food, creating restriction, malabsorption or both, which means you will take in fewer calories over time. After surgery, you will be given a post-surgery meal plan and will slowly increase your food intake as you progress through the diet stages. The bariatric diet is a critical nutritional plan for people who have had bariatric surgery, setting out the types of food and calorie intake needed before and after the procedure.
Because the stomach is now smaller, it takes fewer calories to feel full. However, there is still a lot of confusion about post-op eating guidelines and how many calories are needed after gastric sleeve and bariatric surgery. Dietary guidelines and nutritional needs after surgery, such as those for gastric bypass and gastric sleeve surgery, are essential for a successful recovery and weight loss. Read on for the answer!
How many calories will I need after bariatric surgery?
There is a lot of information about how much and what you should eat after bariatric surgery, but the specific number of calories to take in each day is not that simple. We do not yet have a validated predictive equation for estimating calorie requirements after bariatric surgery, so any calorie targets you have been given or read about are not based on robust scientific evidence. Your calorie intake will also change in the months after surgery. Portion sizes will increase; this is expected and perfectly normal.
Focus more on the quality of the foods you choose than on the quantity. Identify your new hunger and satiety cues. The focus should not be on counting calories, but on a lifelong change – not just another unsustainable diet. That said, monitoring your daily calorie intake matters within the post-operative dietary guidelines for gastric bypass patients, to make sure it supports weight loss while meeting your individual nutritional needs.
Bariatric surgery reduces the amount of food you can eat, but it does not affect the nutritional quality of what you eat. Counting calories is not the most helpful, since the lowest-calorie choices are not always the most nutritious. Because quantity is restricted, quality needs to be high. Specialised dietary plans and resources for bariatric patients help make sure you get the nutrients you need. If you do want a calorie range to keep you on track, here it is:
| Stage | Typical calorie intake | Protein |
|---|---|---|
| Before surgery (very low-calorie diet, under medical supervision) | 450–700 kcal/day | – |
| First week after surgery (usually entirely liquid) | Approx. 400 kcal/day | – |
| Weeks 3–4 | 600–800 kcal/day | 60–80 g/day |
| Several months after surgery | 1,200–1,500 kcal/day | 60–80 g/day |
| 6 months post-op and long term | Approx. 1,500–1,800 kcal/day | – |
In the first week, your post-surgery meal plan will likely be entirely liquid to aid gastrointestinal healing. Your diet will then progress from puréed to soft foods before you resume a solid food diet. As you can see, your calorie intake increases gradually. A very low-calorie diet is often needed before bariatric surgery, typically 450–700 calories per day under medical supervision, to support weight loss and improve surgical outcomes.
Helpful hints to keep you on track
- Avoid snacking/grazing. A snack between meals when you are hungry is perfectly fine, but eating throughout the day out of boredom, tiredness, etc. may hinder your results and keep you from losing weight.
- Eat protein first. Aim for at least 60 grams of protein each day. Since you are eating less food, make sure you get enough protein: include a good source with each meal (eggs, lean meat, poultry, fish, beans or low-fat dairy foods).
- Eat slowly. Each meal should last 20–30 minutes. If you eat too fast, you may eat too much before you realise you are full, which can lead to nausea, vomiting and/or pain or pressure in the shoulder or upper chest.
- Eat small amounts. Eat no more than about 240 ml (one cup) of food per meal. Larger portions risk weight gain and stretching your pouch over time. Using a food scale to weigh your food will help.
- Slowly introduce new foods. Add one new food at a time, so you can determine which foods you can and cannot handle. Certain foods may cause problems after bariatric surgery, though this varies from person to person. Your dietitian can help with questions about specific foods.
- Avoid sugar and fat. With a well-balanced diet of lean proteins, vegetables, low-fat dairy, wholegrains and fruit, you will not have room for less nutrient-dense foods. Try the 10 by 10 rule: eat foods with less than 10 grams of fat and 10 grams of sugar per serving.
And there you have it: your guide to calorie goals and eating guidelines after bariatric surgery. It may seem confusing at first, but you will be absolutely fine as long as you follow this and listen to your healthcare professionals.
These are just guidelines. To succeed on your wellness journey, find the guidelines that work best for you and your long-term success. Everyone's journey is different, and your guidelines may not be the same as someone else's.
Sources
- Mechanick JI, et al. Surgery for Obesity and Related Diseases. 2020;16:175–247.
- Sherf Dagan S, Goldenshluger A, Globus I, et al. Nutritional recommendations for adult bariatric surgery patients: clinical practice. Adv Nutr. 2017;8:382–94.
- Lim HS, Kim YJ, Lee J, Yoon SJ, Lee B. Establishment of adequate nutrient intake criteria to achieve target weight loss in patients undergoing bariatric surgery. Nutrients. 2020;12(6):1774. doi:10.3390/nu12061774
- Kanerva N, Larsson I, Peltonen M, Lindroos AK, Carlsson LM. Changes in total energy intake and macronutrient composition after bariatric surgery predict long-term weight outcome: findings from the Swedish Obese Subjects (SOS) study. Am J Clin Nutr. 2017;106(1):136-145. doi:10.3945/ajcn.116.149112
- Vanoh D, Shahar S, Mahmood NR. Association between nutrient adequacy and psychosocial factors with overall rate of weight loss after bariatric surgery. Asia Pac J Clin Nutr. 2015;24(4):610-619. doi:10.6133/apjcn.2015.24.4.11
This article is for general information only and does not replace personal medical advice. Always discuss your situation, blood test results and supplementation with your bariatric team or healthcare provider.