Five Essential Nutrients for Patients on GLP-1s

Fatigue, nausea, acid reflux, muscle loss, and the dreaded “Ozempic face” are side effects from using glucagon-like peptide 1 (GLP-1) receptor agonists (RAs) such as semaglutide or the dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RA tirzepatide to control blood sugar and promote weight loss. 
But what I’ve learned from working with hundreds of patients on these medications, and others, is that most (if not all) of these side effects can be minimized by ensuring proper nutrition. 
Setting patients up for success requires dietary education and counseling, along with regular monitoring to determine any nutritional deficiencies. Although adequate intake of all the macro and micronutrients is obviously important, there are five nutrients in particular that clinicians should emphasize with their patients on GLP-1 RAs or GIP/GLP-1 RSs. 
My patients are probably sick of hearing me talk about protein, but without the constant reinforcement, many of them wouldn’t consume enough of this macronutrient to maintain their baseline lean body mass. The recommended dietary allowance (RDA) for protein (0.8 g/kg bodyweight) doesn’t cut it, especially for older, obese patients, who need closer to 1.0-1.2 g/kg bodyweight to maintain their muscle mass. For example, for a 250-lb patient, I would recommend 114-136g protein per day. This is equivalent to roughly 15 oz of cooked animal protein. It’s important to note, though, that individuals with kidney disease must limit their protein intake to 0.6-0.8 g/kg bodyweight per day, to avoid overtaxing their kidneys. In this situation, the benefit of increased protein intake does not outweigh the risk of harming the kidneys.
It’s often challenging for patients with suppressed appetites to even think about eating a large hunk of meat or fish, let alone consume it. Plus, eating more than 3-4 oz of protein in one meal can make some patients extremely uncomfortable, owing to the medication’s effect on gastric emptying. This means that daily protein intake must be spread out over multiple mini-meals. 
For patients who need more than 100 g of protein per day, protein powders and premade protein shakes can provide 20-30 g protein to fill in the gaps. Although I always try to promote food first, protein supplements have been game changers for my patients, especially those who find solid food less appealing on the medication, or those who avoid animal protein. 
Clinicians should have their patients monitor changes in their lean body mass using a dual-energy x-ray absorptiometry scan or a bioelectrical impedance scale; this can be a helpful tool in assessing whether protein intake is sufficient. 
Even my most knowledgeable and compliant patients will experience some constipation. Generally speaking, when you eat less, you will have fewer bowel movements. Combine that with delayed gastric emptying and reduced fiber intake, and you have a perfect storm. Many patients are simply not able to get in the recommended 25-35 g fiber per day through food, because fibrous foods are filling. If they are prioritizing the protein in their meal, they will not have enough room for all the vegetables on their plate. 
To ensure that patients are getting sufficient fiber, clinicians should push consumption of certain vegetables and fruits, such as carrots, broccoli, brussels sprouts, raspberries, blackberries, and apples, as well as beans and legumes. (Salads are great, but greens like spinach are not as fibrous as one might think.) If the fruit and veggie intake isn’t up to par, a fiber supplement such as psyllium husk can provide an effective boost.
Use of these medications is associated with a reduction in vitamin B12 levels, in part because delayed gastric emptying may affect B12 absorption. Low dietary intake of B12 while on the medications can also be to blame, though. The best food sources are animal proteins, so if possible, patients should prioritize having fish, lean meat, eggs, and dairy daily. 
Vegetarians and vegans, who are at an increased risk for deficiency, can incorporate nutritional yeast, an excellent source of vitamin B12, into their daily routine. It is beneficial for patients to get bloodwork periodically to check on B12 status, because insufficient B12 can contribute to the fatigue patients experience while on the medication.
Individuals should have calcium on their radar, because weight loss is associated with a decrease in bone mineral density. Adequate intake of the mineral is crucial for optimal bone health, particularly among postmenopausal women and those who are at risk of developing osteoporosis. The RDA for calcium is 1000-1200 mg/d, which an estimated 50% of obese individuals do not take in. 
Although dairy products are well-known for being rich in calcium, there are other great sources. Dark green leafy vegetables, such as cooked collard greens and spinach, provide nearly 300 mg per cup. Tofu and sardines are also calcium powerhouses. Despite the plethora of calcium-rich foods, however, some patients may need a calcium supplement.
Vitamin D deficiency or insufficiency is common among individuals with obesity, so even before these patients start the medications, supplementation may be warranted. The vitamin’s role in promoting calcium absorption, as well as in bone remodeling, make adequate intake essential for patients experiencing significant weight loss.
Clinicians should emphasize regular consumption of fatty fish, such as salmon, as well as eggs, mushrooms, and vitamin D–fortified milks. But unfortunately, that’s where the list of vitamin D–rich foods ends, so taking a vitamin D supplement will be necessary for many patients.
Regularly monitoring patients on GLP-1 RAs through bloodwork to check vitamin levels and body composition analysis can be helpful in assessing nutritional status while losing weight. Clinicians can also encourage their patients to work with a registered dietitian who is familiar with these medications, so they can develop optimal eating habits throughout their health journey.