While taking semaglutide or tirzepatide, sometimes, people eat very few calories. Of course this often leads to a very large amount of weight loss, on the order of 35-30% of the starting body weight. But, is that healthy? What are the risks of eating so little? How do you avoid them? How do you eat very low calories and meet your nutritional needs and stay strong at the same time? After all, we don't just want weight loss, we want strong muscles, bones and brains long term.
We can look to our experience with both very low calorie ketogenic diets and bariatric surgery as two examples to guide us as we build experience with these medications that have only been used for 3 years to treat obesity.
Very Low Calorie Diet
A very low calorie diet is one that is under 800 calories. They have been used for decades for highly effective weight loss of 25 to 30% of starting body weight while preserving lean body mass, targeting visceral fat, and meeting nutritional needs. This is the protocol offered by Rainier Medical since it opened in 2015. It is done using fortified meal replacements intended to meet all nutritional needs with just the addition of 86 ounces of water and an essential fatty acid supplement. The protein shources are highly quality, easily digestible, and highly bioavailable. Rainier Medical has had its results published twice at Obesity Week showing excellent preservation of skeletal muscle mass and nearly 10 years of monitoring body composition analysis and blood work to ensure safety, efficacy, and nutritional health while used with medical supervision to de-prescribe medications and make adjustments as needed. The pitfalls of this approach has been tolerability for people who have lack of satiety or satiation and durability of weight loss. Pairing a modified low calorie diet protocol with incretin mimetics (currently semaglutide and tirzepatide) may be the best of both worlds during weight loss for reducing side effects of medications, avoiding loss of lean body mass, meeting nutritional needs, and maximizing weight loss which can certainly vary.
Gastric Bypass
Some people feel sick when they start semaglutide or tirzepatide and have to discontinue them. This is unfortunate, because we know they are highly effective if they are tolerated. Sometimes, the medications are just not well tolerated. But, the types of food and pattern of eating can have a powerful effect on how you feel when you take these medications, especially in the month after starting them or increasing the dose. After bariatric surgery, there is a specific progression of foods while the GI tract heals and adapts and then functions with a smaller volume and altered digestion. My theory is the same type of diet people use following gastric bypass to heal can be used to adapt to these medications and dosage changes. After all, gastric bypass changes GLP 1 just like these medications do. In a way, these medications have some analogies to gastric bypass but in a medication. The pattern below will avoid stretching out the stomach. People feel poorly with either high fat or heavy foods or a full stomach, typically. Below are guidelines for eating patterns after gastric bypass diet that may help adapt to these medications and help with any side effects.
Long-Term
As we know, these medications are intended for long term use for chronic weight management. So, it is imperative to ensure nutritional needs are met. We have seen from people who have had gastric bypass that complications can rarely arise such as neuropathy, osteoporosis with fragility fractures and liver issues. After gastric bypass, people have blood work to monitor vitamin levels. We know that with obesity itself, there is a higher prevalence of micronutrient deficiencies. Do people need vitamin levels monitored after being on these medications over time and losing large amounts of body weight and consuming low calorie diets? We don’t really know since they are new, but I think it is important to be vigilant and check until we do. One concern is that if these medications are ordered online without medical monitoring, incorporation of blood work and individual health characteristics, there may be missed opportunities for health.
Modified Eating Style
Depending on your tolerance of these medications, here are a few levels of variations. The package insert contains warnings on acute kidney injury, which typically happens when people get dehydrated. So, it is important to have strategies to avoid that. As always, seek advice from your healthcare provider for any questions or concerns.
Liquids:
Protein shakes (high in protein, low in sugar)
Low-fat milk or milk alternatives
Sugar-free pudding or custard (smooth, no chunks)
Creamed soups (strained)
Yogurt (sugar-free, plain)
Smooth fruit or vegetable juice (no pulp)
Soft Foods:
Protein should still be the focus, and all foods should be low in sugar and fat.
Soft scrambled eggs
Mashed potatoes (small amounts, without butter or cream)
Cottage cheese or ricotta cheese
Blended fruits
Soft cooked vegetables
Lean meats (chicken, fish, turkey)
Tofu
Scrambled eggs
Cottage cheese
Well-cooked fruits without skins
Oatmeal or cream of wheat
It's important to chew foods thoroughly to prevent discomfort and ensure proper digestion. These medications reduce stomach motility.
Long Term
Keep portion sizes are small, and meals should be high in protein, low in sugar, and low in fat. Key principles include:
Eating small meals (1/4 to 1/2 cup)
Avoiding high-sugar foods and drinks
Avoiding drinking while eating (wait 30 minutes before or after eating to drink)
Chewing thoroughly and eating slowly
Avoiding tough or fibrous meats and sticky foods like bread and pasta
Foods to include:
Lean proteins (chicken, turkey, fish, tofu)
Vegetables (steamed, soft, or pureed)
Fruits (low in sugar, no skins)
Whole grains in small amounts (quinoa, oats)
General Guidelines
Protein: Focus on high-protein foods (like chicken, turkey, tofu, fish, and eggs) to support healing and maintain muscle mass.
Hydration: Drink plenty of fluids, but avoid drinking with meals. It's important to hydrate between meals to avoid stretching the new stomach pouch.
Vitamins and Supplements: After gastric bypass, your body may have trouble absorbing nutrients, so your doctor will likely recommend lifelong daily vitamins and minerals, including a multivitamin, calcium, vitamin D, and vitamin B12.
Portion Control: Your stomach will function as if it is smaller, so eating small portions is key to avoid stretching the pouch or overeating.
General Considerations
Over the long term, you'll need to continue making healthy food choices. Here’s what to keep in mind:
Avoid high-sugar and high-fat foods to prevent "dumping syndrome," which can cause nausea, diarrhea, and discomfort.
Focus on high-protein, nutrient-dense foods to ensure you're getting enough nutrition.
Exercise regularly to help with weight loss and improve overall health.
Take Back Your Nutritional Health,
Valerie Hope-Slocum Sutherland, MD
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