Drug & supplement interaction

Weight Watchers Diet + Insulin Aspart

Insulin Aspart brand name: Fiasp.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Weight Watchers Diet has a moderate interaction with Insulin Aspart. Following the Weight Watchers diet while taking antidiabetes drugs may increase the risk of hypoglycemia.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Weight Watchers Diet and Insulin Aspart

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTIDIABETES DRUGS

Why this applies to Insulin Aspart

Insulin Aspart falls under ANTIDIABETES DRUGS — the group Weight Watchers Diet interacts with.

Following the Weight Watchers diet while taking antidiabetes drugs may increase the risk of hypoglycemia.
Hypoglycemia has occurred in a small number of patients with type 2 diabetes who are taking antidiabetes medications and following the Weight Watchers Diet. Dose adjustments of antidiabetes medications might be necessary for some people.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to keep in mind if you're following the WW (Weight Watchers) plan while using insulin aspart (Fiasp). The program nudges you toward eating fewer calories and more filling, lower-carb foods. That's great for your overall health, but it means you may be taking in less sugar than your insulin dose was originally set for. Since insulin aspart's whole job is to push blood sugar down, eating less can leave you with low blood sugar (hypoglycemia).

Watch for shakiness, sweating, dizziness, a racing heart, confusion, or sudden hunger. The good news is this is manageable: as you eat differently or lose weight, your doctor may simply lower your insulin dose. Please don't change your insulin on your own, but do tell your doctor or pharmacist you're starting WW so they can adjust things and check your numbers.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. O'Neil PM, Miller-Kovach K, Tuerk PW, et al. Randomized controlled trial of a nationally available weight control program tailored for adults with type 2 diabetes. Obesity (Silver Spring). 2016;24(11):2269-2277. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Weight Watchers Diet Also Interacts With Other Medications

Weight Watchers Diet has 85 moderate known drug interactions in our database — the Insulin Aspart one above is one of them. If you take anything else, check it against the full list below.

Moderate 85 No known interaction 2,745 (incl. Insulin Aspart)
Taking anything else?

Check Another of Your Medications Against Weight Watchers Diet

Covers the 2,830 medications we’ve checked against Weight Watchers Diet. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Insulin Aspart

This page covers Weight Watchers Diet only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Insulin Aspart page lists 239 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate), Agaricus Mushroom (moderate) and Agmatine (moderate).

By severity: 1 major · 208 moderate · 30 minor.

From our pharmacist’s overview on the Insulin Aspart page

“Every one of the 239 supplements listed for insulin aspart (Fiasp) touches the same thing the drug exists to manage, blood sugar, so this list warrants genuine care rather than a quick skim. Most entries add to insulin's glucose-lowering effect, raising the risk of hypoglycemia, and with a rapid-acting mealtime insulin a low can become…”

Reviewed by 2 · Jul 18, 2026

Open the Insulin Aspart interaction page

How much people look this up

Where Weight Watchers Diet and Insulin Aspart Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Weight Watchers Diet
Steady interest

#991 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Insulin Aspart
Top half

#934 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Eating pattern

About Weight Watchers Diet

What is Weight Watchers Diet?

  • Weight loss
  • Weight maintenance
  • Building healthier eating habits
  • Behavioral support for diet change
  • General wellness and lifestyle improvement

Weight Watchers (now called WW) is a commercial weight-loss program built around a points system, food tracking, and group or online support rather than a pill or herbal product. Research generally shows it can help people lose a modest amount of weight and keep some of it off, especially when combined with regular activity. Talk with your doctor or pharmacist before starting any weight-loss plan, particularly if you have a medical condition.

Read the full Weight Watchers Diet monograph & all interactions
Medication

About Insulin Aspart (rDNA Origin) Injection

What Is Insulin Aspart (rDNA Origin) Injection Used For?

Brand name: Fiasp

Insulin aspart is used to improve blood sugar (glucose) control in people with diabetes mellitus. It is approved for both type 1 and type 2 diabetes in adults, and for diabetes mellitus in pediatric patients.

Insulin Aspart Protamine and Insulin Aspart Mix 70/30 is a pre-mixed product that combines a rapid-acting and an intermediate-acting insulin aspart. It is approved to improve blood sugar control in adult patients with diabetes mellitus. It is not recommended for treating diabetic ketoacidosis, and because its ratio of rapid-acting to intermediate-acting insulin is fixed, it does not allow for separate mealtime versus background dose adjustments.

See full Insulin Aspart (rDNA Origin) Injection drug information
Keep checking

Other Drugs & Weight Watchers Diet

Browse every other medication we’ve checked against Weight Watchers Diet — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
85Moderate
0Minor
2,744No known interaction
85 Moderate 2,744 No interaction
Moderate

85 interactions

Showing 60 of 85 moderate interactions — see all 85 on the Weight Watchers Diet page.

No interaction 2,744 drugs checked — show the list

We also checked Weight Watchers Diet against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,744 medications checked with no known interaction — see the full Weight Watchers Diet list.

See the full Weight Watchers Diet interactions page
See every supplement checked against Insulin Aspart, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Weight Watchers Diet monograph › Uses, safety, and every drug interaction in one place Insulin Aspart supplement interactions › Every supplement checked against Insulin Aspart, ranked by severity Insulin Aspart (rDNA Origin) Injection drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Following Weight Watchers Diet While Taking Insulin Aspart: Common Questions

Can you follow Weight Watchers Diet while taking Insulin Aspart?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Weight Watchers Diet and Insulin Aspart interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Insulin Aspart and Weight Watchers Diet?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.