How Effective is Topamax (Topiramate) for Weight Loss

Topamax for weight loss

Topamax for weight loss is indicated and approved by the FDA only in the combination pill, Qsymia. Qsymia contains fixed doses of Topiramate and phentermine.

Topamax is the brand name of Topiramate. It is primarily used to treat patients with seizures. However, it has also been approved by the FDA for the prevention of migraine attacks and in combination with phentermine (as Qsymia) for weight loss.

When combined with Phentermine, a strong anorexiant drug, the weight loss effect of phentermine is enhanced. It is not recommended in patients who are allergic to the drug and those with the following underlying conditions:

  • Angle-closure glaucoma
  • Hyperthyroidism
  • Pregnant women, and
  • the concomitant use of it with an MAO inhibitor

Topamax is indicated for the treatment of obese individuals (in combination with phentermine) only if:

  • The BMI of the individual exceeds 30 kg/m², or
  • The BMI exceeds 27 kg/m² in the presence of one or more weight-related conditions. These include:
    • Diabetes or prediabetes
    • Hypertension
    • Dyslipidemias, and
    • a waist circumference of more than 88 cm in women and more than 102 cm in men.
bmi chart
BMI chart: Match your height and weight. The green area indicates obesity, the grey area suggests overweight, and the area to the left (uncolored) is normal BMI.

Topamax (Topiramate) MOA (Mechanism of action):

Topamax (topiramate) is primarily used to treat seizures. The four different mechanisms of the drug’s action in controlling seizure activity are listed here:

  • Topiramate acts by blocking the activity of voltage-dependent sodium channels
  • It also enhances the activity of GABA-A receptors (Gamma-aminobutyrate)
  • Antagonizes AMPA/kainate subtypes glutamate receptors
  • Inhibits carbonic anhydrase enzymes, especially isozymes II, and IV.

How Topamax (topiramate) causes weight loss?

The exact mechanism of action of topiramate is not known, however, topiramate has been shown to alter the utilization of food and energy. Although its effects on energy utilization have been proven in animals, this effect is not clear in humans. Because of its effects on neuropeptide Y and the hunger centers in the brain, topiramate exerts its effects by reducing cravings and appetite.

Topamax suppresses hunger

In addition, topiramate is approved for weight loss when used with phentermine. It is available by the brand name of Qsymia that contains fixed doses of Topiramate and Phentermine. Phentermine is a stimulant drug that suppresses appetite and increases the basal metabolic rate of the human body.

When used for the treatment of migraine prevention and epilepsy, weight loss is considered by most as the side effect of topiramate. Thus, in combination with phentermine, this weight loss effect has been considered as a positive effect in obese and overweight patients.

As monotherapy, topiramate has not been approved for weight loss

How effective is Topamax for weight loss?

Topamax induces weight loss by suppressing appetite and increasing the metabolic rate. Thus, individuals feel less hungry. In addition, with topiramate, people burn calories faster than usual. When a negative energy state is achieved, people start losing weight.

Rapid weight loss is associated with serious complications. In the first few days of a weight loss regimen, rapid weight loss may occur. This is usually due to the extra fluid loss from the body. However, as fats are burned, weight loss may be very slow. At this stage, the person needs to be devoted and consistent in order to achieve significant weight loss in the longer run.

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The weight loss effect of Topamax is dependent on the dose. It is usually administered initially in a dose of 25 mg per day and increased to a maximum dose of 200 mg per day.

Although Topamax monotherapy has not been studied in obese individuals as a weight-loss drug,  weight loss was documented as a side effect when used to treat seizures or for migraine prophylaxis.

In one study, Topamax resulted in a dose-dependent weight loss in patients treated for migraine [Ref].

percent change in weight with topiramate

Percent change in weight with topiramate compared to placebo medicine.

When Topamax was administered to bipolar patients in an average dose of 195 mg per day, patients lost weight about 22 pounds over the study period. Topamax may cause some weight loss within weeks, however, in most patients weight loss is evident when the drug is taken for at least four months.

Since Topamax is indicated for weight loss in the combination pill, Qsymia, it has been studied with phentermine.

How effective is Qsymia (Phentermine/ Topiramate) for weight loss?

Qsymia was studied in two clinical trials [Ref]. One trial recruited only obese patients without comorbid conditions such as diabetes. Another trial recruited obese and overweight patients with comorbid conditions such as diabetes and dyslipidemias.

At one year of follow-up, a significant number of patients opted out of the trials because of the drug side effects. However, at one year, significant weight loss occurred in the participants who took Qsymia compared to placebo.

qsymia and topiramate topamax for weight loss
Weight loss in the Qsymia low and high doses groups at one year in Obese individuals compared to placebo

In the above clinical trial, patients were obese with a BMI exceeding 30 kg/m² and had no other comorbid conditions. the mean baseline weight of the study participants was 116 kgs and the mean BMI was 42 kg/m². 83% of the study participants were females.

In the second study, patients were either obese with a BMI exceeding 30 kg/m² or were overweight with a BMI exceeding 27 kg/m² plus had one or more weight-related conditions. These included diabetes or prediabetes, a waist circumference of more than 88 cm in women and 102 cm in men, raised triglycerides (200 to 400 mg/dl), or receiving two or more lipid-lowering drugs, or had hypertension.

qsymia topiramate topamax weight loss
Qsymia weight loss in study 2. The mean weight of the participants was 103 kgs and had a BMI of 36.6 kg/m².

How long does it take to lose weight on Topamax?

Topamax suppresses appetite and may increase the body’s ability to utilize calories efficiently. It does not cause rapid weight loss. In motivated patients, when combined with exercise and a low caloric diet, weight loss may be noticed even during the first few weeks of treatment initiation.

However, it usually takes about 12 weeks for a person to lose enough weight to be noticed. The manufacturer recommends discontinuing Topamax or increasing the dose if less than 3% body weight has been lost over 12 weeks. If less than 5% of the body weight has not been lost after 24 weeks, treatment should be discontinued.

In clinical trials, weight loss of about 22 pounds was evident after four weeks of the treatment.

Topamax Tablets and Available Formulations:

Topamax is available as sprinkle capsules in a dose of 15 and 25 mg and tablets formulation as 25, 50, 100, and 200 mg. The doses schedule changes according to the indication of use. Treatment is usually initiated in lower doses of 25 mg once daily and titrated at weekly intervals by 25 mg to 400 mg per day maximum.

Topiramate is also available in combination with Phentermine by the brand name of Qsymia. Qsymia is available in four fixed-dose combinations. These include:

  • Phentermine/ Topiramate 3.75/ 23 mg
  • Phentermine/ Topiramate 7.5/ 46 mg
  • Phentermine/ Topiramate 11.25/ 69 mg
  • Phentermine/ Topiramate 15/ 92 mg

Dosage of Topamax for weight loss:

Topamax is not indicated to be used alone for the treatment of weight loss. In obese patients who have migraines, seizures, or patients on psychiatric medications, Topamax may provide the additional benefit of weight loss.

The maintenance dosage of Topamax recommended for the treatment of Seizures is as high as 400 mg daily in two divided doses. For migraine prevention, it is usually recommended in a maximum dose of 50 mg twice daily.

Topamax dosage for weight loss is almost similar to that used for the prevention of migraines. It is not indicated to be used alone for weight loss. The combination pill Qsymia contains Phentermine and extended-release topiramate is approved for the treatment of weight loss. The dosage of Topamax for weight loss is basically the same as the dose of Qsymia for weight loss.

Dosage of Qsymia for weight loss:

Qsymia is administered in a dose of 3.75/23 mg once daily in the morning for 14 days. After 14 days, if the drug is well tolerated without any increase in the incidence of side effects, the dose is increased to 7.5/46 mg once daily.

Usually, the dose of 7.5/46 mg is continued for a minimum of 12 weeks. If no significant weight loss has been observed, the dose is further increased at an interval of 14 days to11.25/69, and then to the maximum dose of 15/92 mg after another 14 days.

Treatment is usually discontinued if no significant weight loss has occurred after taking the maximum dose of Qsymia for 12 weeks or more. The manufacturer recommends discontinuing Topamax (Qsymia) if weight loss of 5% or more has not been documented.

The best time to take Qsymia is in the morning after breakfast. It can be taken until mid-day, but not later than that because phentermine (and so Qsymia) is a stimulant drug. It may cause insomnia that can increase stress and anxiety.

Will you gain weight after Topamax discontinuation?

Yes. Most patients experienced weight gain after six months of Topamax discontinuation. Weight gain is more rapid in individuals with unhealthy dietary habits. To maintain weight and not regain it, the following simple lifestyle changes are important to follow:

  • Avoid taking beverages, sugars, and refined carbohydrates. Take proteins, fresh salads, fruits, and vegetables.
  • Perform aerobic physical activities such as jogging, running, cycling, swimming, or gardening. Regular exercise of at least 30 minutes can be helpful in lowering body weight, blood pressure, and reduces stress and anxiety.
  • Get enough sleep to lowers your stress level. It also replenishes your energy and helps you exercise efficiently.
  • Reduce stress by doing meditation, perform prayers, doing charity work, and exercise. Lowering your stress may make you emotionally strong and help you in losing weight.

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What do you think?

Written by Diabetes Doctor

I am an Internist practicing medicine for the last fifteen years. Over the years, I have learned that medicine is not about prescribing pills. True medical practice is helping people.
I do prescribe pills as well but the best results I get are when I motivate people to overcome their problems with little changes in their lifestyles.
Since most of my patients are obese, have diabetes, hypertension, high cholesterol levels, I am writing at when free.
Dibesity, I know the correct word is diabesity. Ignore this! Be with us.

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