The keto diet is incredibly popular for weight loss and it might seem appealing try it, even after bariatric surgery. I’m asked all the time, “Should I try the keto diet after weight loss surgery?” So I figured we would dig into the research a little bit.
If you’re considering trying the keto diet after gastric bypass surgery, there are some important things to think about before jumping into this way of eating. It may be helpful for weight loss but maintaining proper nutrition is critical after bariatric surgery, and should remain a priority when trying nontraditional eating patterns like the keto diet.
What is the Keto Diet?
“Keto” is short for the ketogenic diet, which has become a popular way of eating for weight loss and other health reasons over the past decade. Medically, the keto diet has been used to help treat epilepsy in children since the 1920s, and has seen a lot of success in this area.
The ketogenic diet works by relying on ketosis, a physiological state in which your body begins fueling itself via ketones from stored fat instead of glucose (sugar) from carbohydrates. Interestingly, your body shifts into a ketosis state, right after weight loss surgery since food intake is low.
Carbs are your body’s primary source of energy. In fact, your body stores extra carbs for later use whenever a fuel source is needed.
Ketosis is triggered by a very low intake of carbohydrates. The ketogenic diet supports the achievement and maintenance of this state.
The keto diet often results in weight loss due to this metabolic shift. It can be particularly successful in helping manage obesity, as it usually does help people lose weight. This understandably makes it an attractive diet for people wanting to achieve and maintain a healthy weight following gastric bypass surgery.
The basic foods consumed on the keto diet include eggs, meat, fish, avocados, nuts, seeds, low-starch vegetables like leafy greens and tomatoes, some low-carb dairy foods and a few low-carb fruits like berries.
This means that high-carb fruits, starchy vegetables (e.g., potatoes, corn, peas, squash), legumes like beans, as well as grains and breads are not permitted.
Potential Benefits of Keto After Bariatric Surgery
Although the keto diet can be challenging to maintain, especially after bariatric surgery, many people report experiencing benefits by adopting this way of eating.
Following a bariatric keto diet plan may help some people feel fuller for longer between meals and more satisfied after eating. This may be one reason why the keto diet is a successful option for weight loss.
A 2017 study among 50 patients who had gastric bypass between Jan 2010 and Dec 2013 found that a low-calorie keto diet was beneficial for weight loss among patients who stopped losing weight after bariatric surgery.
Some research reports potential benefits like improved mood, increased energy levels, clearer skin, more stable blood sugar levels and hunger control, improved cardiovascular health, and even potentially better brain function.
As part of its restricted menu, the keto diet doesn’t allow added sugar or highly processed packaged foods and refined carbohydrates, which don’t offer any health benefits anyway. Usually these food items are discouraged on a traditional bariatric diet anyway.
Potential Downsides of Keto After Bariatric Surgery
As mentioned, the keto diet can be very restrictive and require an extra layer of planning on top of an already strict post-bariatric diet.
The keto diet is inherently high in fat (usually around 70% of your calories), making it possible to displace other important macronutrients in your diet, like protein, with the limited caloric intake after surgery.
It’s important to insure that you’re choosing healthy fats if you do choose to follow a keto bariatric diet. A long-term, high-fat diet may be linked to an increased risk for kidney and heart problems, as well as insulin resistance. It may also lead to steatorrhea, or fatty diarrhea, which lowers nutrient absorption due to the high rate at which food travels through your gastrointestinal tract.
Along those same lines, dumping syndrome is a common risk after bariatric surgery, and a keto diet may put you at higher risk for experiencing it due to its high fat content. Dumping syndrome affects up to 85% of gastric bypass patients at some point, which typically results from eating foods that are either too high in refined sugar or fat-rich foods like dairy products, fried foods, and certain fats. Food moves quickly through your digestive system (specifically due to the rapid emptying of food your gastric pouch into the small intestine), which often results in unpleasant feelings like low blood sugar, nausea, abdominal fullness, diarrhea, and cramping.
Because the keto diet is often based on animal-derived products and restricts grains and high-carb fruits and vegetables, this can result in a low intake of plant foods. Plants are high in fiber, antioxidants, and other healthy phytochemicals important for preventing constipation, chronic disease, and maintaining long-term health.
Switching to keto after bariatric surgery can cause some unpleasant side effects, commonly referred to as the “keto flu”. Many people report experiencing bad “keto breath” caused by the switch to ketosis. Other common side effects include muscle cramps, weakness, headaches, and dehydration, thought to be related to a loss in electrolytes as well as dehydration. Keto flu symptoms can last for several weeks.
The keto diet may also increase your risk for dehydration, and consequently constipation and kidney stones.
Although the keto diet does typically result in weight loss, it’s important to realize that this doesn’t necessarily mean it’s causing long-term fat loss. Initial weight loss on the keto diet is primarily due to loss of fluid in the body, a loss that can be quick up front, but doesn’t last forever. Should you return to eating your typical diet, you will likely regain what you lost as well as the fluid loss you experienced initially by going keto.
Lastly, although the keto diet itself has been researched for its benefits and success in supporting weight loss, the keto diet after gastric bypass specifically lacks long-term research. This makes it difficult to determine whether keto after bariatric surgery is a good idea for long-term use.
Keto Diet vs. Bariatric Diet
You might be wondering how the ketogenic diet differs from a traditionally prescribed bariatric diet.
The American Society of Metabolic and Bariatric Surgery (ASMBS) recommends the following when it comes to a general post-bariatric diet:
- Eat at least 60-90 grams of protein per day, incorporating protein-rich foods at every meal and snack
- Good sources of protein include meats, eggs, dairy products, tofu, beans, and lentils, as well as protein shakes
- Be careful about how much fat you’re eating after surgery, as it may not be well tolerated by every bariatric patient
- Limit refined carbohydrate foods like white breads and pastas, packaged snack foods, and sugary sweets
- Pay attention to hydration needs (usually around 64 ounces or more per day), as dehydration is the primary reason for hospital readmission after bariatric surgery
A keto diet has some pretty significant variations. The general macronutrient breakdown of a keto diet is around 70% fat, 25% protein, and 5% carbs. It incorporates around 20 grams of net carbs, meaning the carbs leftover after fiber intake is subtracted (as this doesn’t affect your blood sugar like other carbs do).
It’s easy to include unhealthy fats as part of the keto bariatric diet, simply because this is a high-fat diet by nature. However, it’s a good idea to moderate your intake of unhealthy foods high in saturated and trans fats like fast food, cheeseburgers, and bacon.
Rather, some healthy fat choices to incorporate on a keto bariatric diet include salmon, extra virgin olive oil, and avocados. Nuts and seeds are also on this list, but may not be well-tolerated in the early stages after bariatric surgery, so it’s important to incorporate them only when appropriate.
Sample Bariatric Keto Diet Plan
Your bariatric keto diet plan should be unique to your needs and preferences. Below is a sample outline of how you could potentially plan your day’s intake and include the necessary nutrients.
Breakfast: Hard-boiled eggs and roasted salmon
Snack: Cottage cheese and avocado slices
Lunch: Deli meat and cheese rollups made with leaf lettuce
Snack: String cheese and cubed baked tofu
Dinner: Roasted asparagus and chicken breast with extra virgin olive oil
Drinks: Unsweetened decaffeinated coffee and tea, plain water
Keep in mind that your portion sizes, food consistencies, and taste preferences may differ depending on your stage of post-op recovery, dietary tolerance, and nutrient needs. It is highly recommended to work closely with a bariatric registered dietitian to make sure your keto bariatric diet plan is appropriate for you.
Should You Try Keto After Gastric Bypass?
How you tolerate and manage the keto diet after gastric bypass surgery is personal. You may feel like the keto diet is a sustainable way to eat in the long term without putting your health at risk, in which case it could work well for you.
If you decide to go this route, I encourage you to focus more on healthy fat options such as salmon, avocado, nuts, and olive oil and include lots of dark leafy greens. I support this way of eating more than bacon for breakfast, double cheeseburger protein style for lunch, and prime rib for dinner. Plus make sure to talk your health professionals about making the switch.
If keto diet becomes just another crash diet that results in weight gain when you return to previous eating habits then this diet is not for you. You have to enjoy eating this way for the long term for it to be effective. It may also displace important macronutrients like protein, and emphasize fats that could be problematic.
You could try a modified version of the keto bariatric diet, increasing your carbohydrate and plant food intake to reap associated health benefits while also supporting sustained weight loss.
Just be sure to prioritize your nutrient needs, including the vitamin and mineral supplements necessary for your long-term health after bariatric surgery.
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