Farxiga (dapagliflozin) and metformin are primarily prescribed for managing type 2 diabetes, heart failure, and chronic kidney disease. However, emerging research suggests a potential side effect of Farxiga and metformin, particularly when used in combination, may be modest weight loss. This article delves into the mechanisms by which these medications might influence weight, summarizes available evidence, and addresses important considerations for individuals exploring these options.
Understanding Farxiga and Its Mechanism of Action
Farxiga (dapagliflozin) belongs to a class of drugs known as sodium-glucose cotransporter-2 (SGLT2) inhibitors. These inhibitors work by blocking the kidneys from reabsorbing excess sugar back into the bloodstream. Consequently, the excess sugar is excreted through urine. This process not only lowers blood sugar levels but also leads to a loss of calories, potentially contributing to weight loss.
Under normal circumstances, the kidneys filter sugar out of the blood and reabsorb most of it back into the system. Farxiga blocks part of that reabsorption process. Instead of holding onto the extra glucose, your kidneys let more of it pass out of your body through urine. It’s estimated that people taking SGLT2 inhibitors like Farxiga excrete about 75 grams of sugar a day this way, or roughly 300 calories. The weight loss comes from your body losing calories, along with the sugar that’s excreted. This creates a metabolic shift where your body has to find a new source of energy.
Farxiga is typically taken as a once-daily oral tablet. The maximum recommended dose is 10 mg per day, regardless of the condition being treated. Many patients start at the 5 mg dose so their doctor can monitor how well they tolerate the medication and check for potential side effects.
Metformin: A Common Diabetes Medication with Weight Loss Effects
Metformin is a widely used medication for the treatment of type 2 diabetes. It works through both adenosine monophosphate-activated protein kinase (AMPK)-dependent and AMPK-independent mechanisms, inhibiting enzymes related to gluconeogenesis and lipogenesis, while also having antineoplastic effects, delaying the aging process, and regulating gut microbiota
Read also: Weight Loss with SGLT2 Inhibitors
Beyond its effects on glucose, metformin has been suggested by some studies to result in weight loss.
The Potential for Weight Loss with Farxiga Alone
While Farxiga is not specifically designed as a weight loss drug, clinical studies have demonstrated a potential for modest weight loss. In these studies, individuals taking Farxiga alone, at either 5 mg or 10 mg daily, experienced an average weight loss of about 6 pounds over a 24-week period.
Synergistic Effects: Combining Farxiga and Metformin for Enhanced Weight Loss
When Farxiga is combined with other medications like metformin, weight loss can be even more noticeable.
A study aimed to determine if the combined treatment with dapagliflozin and metformin is more effective than monotherapy with metformin for weight loss in patients with class III obesity and prediabetes or diabetes who are awaiting bariatric surgery. This randomized phase IV clinical trial included patients with diabetes or prediabetes who are between the ages of 18 and 60 years and exhibit grade III obesity (defined as body mass index ≥ 40 kg/m2). Patients using insulin were excluded. Subjects were randomized to one of two groups as follows: 1) metformin tablets 850 mg PO bid or 2) metformin tablets 850 mg PO bid plus dapagliflozin tablets 10 mg PO qd.
Research Findings on Farxiga and Weight Loss
As monotherapy in patients with T2D, weight loss ranges from 2 to 3 kg; meanwhile, in a 104-week, randomized, double-blinded study of dapagliflozin versus glipizide as add-on therapies to metformin, weight reductions of up to 5.1 kg (95% CI -5.7 to -4.4 kg) without regain (at least for 2 years) have been reported.
Read also: Berberine and Metformin
Other studies have shown that dapagliflozin is as effective as metformin for weight loss. In a 12-week, randomized, parallel-group, double-blind, placebo-controlled study, patients assigned to dapagliflozin 10 mg daily presented a 2.7% reduction in body weight (95%IC -3.5 to -1.8%) as compared to a weight loss of 1.7% in those assigned to the metformin group (95%CI -2.4 to -0.9%) and 1.2% in patients assigned to placebo (-2.0 to -0.4%).
In a systematic review by Orme et al., in patients previously treated with sulfonylurea, dapagliflozin induced a 1.54 kg weight loss (95%CI -2.16 to -0.92 kg), compared to patients treated with GLP-1 (loss: -0.65 kg, 95% CI -1.37 to 0.07 kg) and a DPP4 inhibitor (gain of 0.57 kg, 95% CI 0.09 to 1.06 kg). Furthermore, the addition of dapagliflozin in patients already treated with metformin and sitagliptin resulted in a 2.1 kg reduction (95% CI -3.2 to -1 kg) compared to placebo.
Important Considerations
Not a Primary Weight Loss Medication
Farxiga is not a medication designed specifically for weight loss, but research shows it can lead to modest weight loss of around 4 to 5% of body weight. The weight loss effect is generally smaller than newer medications like GLP-1 receptor agonists.
Lifestyle Modifications are Crucial
Farxiga works best when a person eats fewer calories. For those who are candidates, Farxiga may be an option to support sustainable, long-term weight management when paired with a balanced diet, regular exercise, and behavior change strategies. A balanced diet with lean proteins, fruits and vegetables, fiber-rich carbs, and healthy fats works well alongside Farxiga. Combine that with regular physical activity, anything from daily walks to structured exercise, and you can boost results.
Potential Side Effects
Farxiga can cause side effects that are typically mild to moderate and manageable at home. These effects are usually tied to how Farxiga works, removing extra sugar through your urine.
Read also: Comprehensive Study: Metformin and Phentermine/Topiramate
Serious urinary tract infections (UTIs) - Farxiga increases sugar in the urine, which can create conditions for bacterial growth. Ketoacidosis - Farxiga may rarely cause a dangerous buildup of ketones, even if blood sugar isn’t very high. Low blood sugar (hypoglycemia) - This usually happens only when Farxiga is taken with insulin or other diabetes medicines. Severe bacterial infections in the genital area - Rare tissue infections can develop in the genital or surrounding area. Farxiga (dapagliflozin) may cause acute kidney injury. Signs to watch out for include urinating less or swelling in you legs or feet.
Cost and Availability
Without insurance, the list price for Farxiga is around $600 for a month’s supply, but you can get it cheaper through different discount programs. Insurance coverage and savings programs can help bring down the cost, but it is unlikely to be covered for weight loss, as coverage generally only applies when the drug is prescribed for conditions like diabetes.
The Farxiga® Savings Card allows eligible commercial insurance holders to pay as little as $0 per month, with a capped savings amount (often up to $175 per month). Prices vary, but can range from $332 to $619 for a 30-day supply of 10 mg tablets based on GoodRx.
Individual Variability
Some people notice weight changes with Farxiga quite early. Weight loss with Farxiga is gradual. Most people notice modest changes within 3 to 6 months, especially when the medication is paired with healthy eating and regular activity.
Long-Term Use and Discontinuation
Farxiga is meant for long-term use when prescribed for diabetes by your healthcare provider. Many people take it safely for years with regular check-ups. When it comes to weight loss, though, there isn’t clear research yet on how long Farxiga can be used safely for that purpose.
Farxiga doesn’t usually cause withdrawal symptoms, but you should not stop on your own. Talk with your doctor first so they can adjust your plan safely.
Contraindications
Patients using insulin will be excluded from combined treatment with dapagliflozin and metformin.