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Keto Diet After Bariatric Surgery

Keto Diet After Bariatric Surgery

Most likely, you have run across the keto diet at some point in your weight loss journey. The keto diet is widely popular for its weight loss results, making it seem like an appealing option for people who have gone through weight loss surgery. Along with weight loss results, people often report improved energy levels, increased satisfaction after meals, and better control over their blood sugar. Before you jump all in, it is important to understand what the diet entails and the benefits and drawbacks of a keto diet after bariatric surgery.

What is The Keto Diet?

The Ketogenic Diet, more commonly known as the Keto Diet, is a low-carb, high-fat diet. People who follow this diet have to be very strict in maintaining a minimal intake of carbohydrates and increasing your healthy fats intake. The goal of restricting carbohydrates is to put your body into ketosis, a state where your body becomes highly efficient at burning fat instead of using energy from glucose.

Under normal conditions, the body gets most of its energy from glucose, or blood sugar, resulting from carbohydrates in our diet. In ketosis, the liver converts fat into ketones, which are then used as a fuel source. By using energy from our stored fat as opposed to energy from carbohydrates, people often lose weight.

Avocados are a good source of healthy fat and are a popular choice on keto menus.

Foods To Eat on the Keto Diet

The keto diet allows you to eat foods that have protein and are high in fat. Generally, your protein intake is not supposed to be high on this diet. Here is a list of foods that are acceptable on the keto diet.

  • Meat - Unprocessed meat is a good source of protein. However, processed meats like sausage and lunch meat can contain carbs. Therefore, it is best to stick with items like unprocessed beef, chicken, and turkey.
  • Fish and seafood - Fatty fish like salmon and mackerel are allowed on this diet because they contain high-fat content and have essential nutrients like omega-3's. Fish should not have bread, as that includes carbs.
  • Eggs - You can eat eggs any way you choose, and they are a good source of protein without carbohydrates.
  • Vegetables - Generally, vegetables that grow above the ground are allowed on the keto diet. Make meals that include veggies like cabbage, broccoli, avocado, and zucchini.
  • High-fat dairy - Items like heavy cream, butter, and high-fat cheese are allowed on the keto diet. Milk is also permitted in minimal amounts as the sugar in milk quickly takes away your allotted carbohydrate intake each day.
  • Nuts and berries - These items are allowed in moderation, although it is easy to eat too many of both as they don't make you feel full very quickly.

Cooking your foods in natural fats like olive oil and coconut oil is another way to increase your fat intake. Remember, the keto diet's goal is to get most of your calories from fats as they make you feel full and help you get into a ketogenic metabolic state.

The keto diet is a low-carbohydrate diet. Therefore, things like bread and pasta are not allowed.

Pros of the Ketogenic Diet After Bariatric Surgery

People usually undergo bariatric surgery to help them achieve a healthier weight and lifestyle. Often, bariatric surgery also helps manage and even treat certain health conditions like obesity and sleep apnea. With weight loss being the primary goal for most bariatric surgery patients, the keto diet may be an appealing option, as it is an effective way to lose weight. Let's explore the pros of the keto diet after bariatric surgery.

Weight Loss

The keto diet is well known for helping people lose a significant amount of weight. For people struggling to continue to lose weight after bariatric surgery, the keto diet may be beneficial in helping to shed additional pounds. Many bariatric surgery patients find their weight loss plateaus after several months following surgery. Therefore, additional interventions are sometimes necessary, such as dietary changes. In one smaller study, patients whose weight plateaued after having gastric band surgery found they could continue to lose weight once they started a high-protein, low carb keto diet.

Lowers Cholesterol and Blood Sugar

High cholesterol can be a problem for just about anyone, but people with obesity have a greater likelihood of struggling from adverse events due to high cholesterol. Similarly, obesity often goes hand-in-hand with insulin resistance (leading to type 2 diabetes). In a study on the long-term effects of a keto diet in obese people, the keto diet decreased the patient's BMI's and lowered their "bad" cholesterol (LDL) and triglycerides. In contrast, "good" cholesterol (HDL) increased.

Similarly, the study also found that patients following a keto diet had lower blood sugar levels. These improvements can make a significant difference in a person's overall health and well-being.

Type 2 diabetes is common in people with obesity. A ketogenic diet may naturally improve blood sugar levels.

Increases Satiety

The keto diet is well-known for having a hunger-reducing effect. While the exact mechanism for increasing satiety is not well understood, the high-fat content of approved foods on this diet likely makes you feel full and satisfied more quickly. Therefore, a person following the keto diet is less likely to overeat and snack in between meals.

Overall Health Improvements

People on the keto diet claim to have more energy, clearer skin, think more clearly, and are less irritable.

Cons of the Ketogenic Diet Following Bariatric Surgery

All of the keto diet pros seem to make complete sense for anyone looking to improve their weight and overall health. But before you jump on the keto bandwagon, it is essential to know the downsides of this diet, especially for people who have had bariatric surgery.

Nutritional Deficiencies

One of the biggest concerns for patients (and their surgeons) after bariatric surgery is nutritional deficiencies. Because surgery alters the gastrointestinal system in some (or many) ways, you are less likely to absorb the nutrients you need to be healthy. Similarly, because your food portions are severely restricted, it can make it that much harder to get the nutrients you need. For example, 45% of weight loss surgery patients are deficient in iron, and 60-80% are low in vitamin D. Bariatric surgery patients need to have a personalized vitamin regimen to get all of their essential nutrients.

People who have bariatric surgery will need to have a personalized vitamin regimen for the rest of their life.

Not Enough Protein

Protein is paramount after bariatric surgery. The American Society for Metabolic and Bariatric Surgery recommends that WLS patients get at least 60-80 grams of protein daily. Protein is essential because it not only maintains essential body functions, but it helps your body burn fat instead of muscle. Additionally, because limiting calories is crucial for weight loss after surgery, most of your calories should come from protein-rich sources.

The ketogenic diet does not allow for a sufficient amount of protein intake for bariatric surgery patients. Therefore, if you choose to follow this diet after surgery, you will need to modify the diet to meet your recommended daily protein requirements.

Malabsorption of Fat

The keto diet is a high-fat diet, which helps put your body into ketosis. However, people with altered gut hormones and digestive tracts can struggle to digest high-fat foods. Fatty foods can increase the rate at which your food moves throughout your digestive tract, leading to nutritional deficiencies and unpleasant side effects like dumping syndrome.

Ketogenic Flu

Although this is not a technical term, many people report feeling flu-like in the first few weeks after starting the keto diet. Symptoms you may experience include muscle weakness and cramping, headaches, and feeling dehydrated. Once your body adjusts to the diet, you generally begin to feel better as long as you meet your nutritional needs.  

Furthermore, people may also experience constipation because much of the diet consists of animal fats. Therefore, people tend to focus less on fruits and vegetables, rich in fiber, vitamins, and antioxidants. Without these beneficial nutrients, it can be challenging to regulate your bowels.

Each person has unique nutritional needs following bariatric surgery.

What is the Best Diet After Bariatric Surgery?

Every person is unique in their nutritional needs after bariatric surgery. Therefore, there is no one-size-fits-all diet that works for every WLS patient. The keto diet may undoubtedly benefit some people after bariatric surgery and may be the ticket to helping people that plateau at a specific weight. However, it may not work for other patients because the foods are too high in fat, and there are not enough plant fibers to support digestion.

If you are searching for the best bariatric surgery diet for you, meet with your bariatric surgeon and nutritionist to make sure you are supporting your body's needs while meeting your weight loss goals.

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Julia Rae Walker, RN, BSN, BA


Julia is an experienced critical care nurse with a background in pediatric and adult patient populations. Her passion is helping patients maximize their quality of life.

Gintas Antanavicius, MD, FACS, FASMBS

Medical Reviewer

Dr. G is a co-founder of BariBuilder. A US-based expert surgeon with over 10 years of bariatric experience, he regularly publishes research in medical journals like SOARD, Obesity Surgery, etc.