Insight Reports / GLP-1 and the Kellogg Basket

When a shopper starts GLP-1, the Kellogg basket quietly re-sorts.

That GLP-1 weighs on snacks and cereal is already widely known. The useful questions are the specifics: which products lose ground, by how much, how soon after a shopper starts, and where the spending goes instead. This report works through them with 2,000 real Amazon shoppers who bought GLP-1 support supplements — reading each cart before and after, in aggregate and one receipt at a time — using Kellogg as the worked example.

2,000
GLP-1 shoppers tracked
−8%
Kellogg cereal, share of basket
+7%
Protein drinks, share of basket
1.9M
Amazon purchases analyzed
Key takeaways
  • The basket re-sorts toward protein. After a shopper starts GLP-1, share moves out of cereal and snacks and into protein drinks, bars, and Greek yogurt — each up about 7–8% of basket in our panel.
  • Kellogg's categories soften more than the averages around them. Kellogg cereal is down about 8% of basket and Kellogg snacks about 6.5%, and roughly one in three prior Kellogg buyers eased off in the year after starting.
  • The protein demand mostly lands with other brands. Premier, Quest, and Atkins lead the cohort's protein purchases; Kellogg's own protein products (Special K Protein, RXBAR) appear far less often.
2,000 shoppers, measured before and after
The study follows 2,000 Amazon households identified by one behavior: each bought a GLP-1 support supplement — the fiber, protein, and metabolism products marketed to people starting or substituting for GLP-1 drugs.

They're established shoppers, not survey respondents, with a median of roughly 650 orders each between 2019 and 2026. For each household, the first dated GLP-1 purchase sets a reference point, and the year before is compared with the year after. One caveat: Amazon shows only part of any household's grocery basket, so these figures are best read as directional signals, not a full census — what stands out is how consistent the direction is across the cohort.

What leaves the basket
If GLP-1 simply shrank baskets evenly, this would be a broad category story. Instead the softening is uneven — it leans toward refined-carb cereal and salty-and-sweet snacks, and Kellogg's two areas slip a little more than the averages around them.
Change in share of basket, before → after starting GLP-1
Per-category share of all purchases, averaged across shoppers. Growth to the right, decline to the left.
Where it goes instead
The share that leaves cereal and snacks tends to reappear in ready-to-drink protein, bars, and high-protein yogurt — up roughly 6–8% of basket. Much of that demand sits in categories Kellogg doesn't play in heavily yet.
Protein brands the cohort bought after starting (purchases)
Shakes, powders, bars, and high-protein yogurt. Kellogg-owned brands highlighted.

The shopper Kellogg softens with in the cereal aisle is often the same shopper Premier (BellRing), Oikos (Danone), Quest, and Atkins gain in the protein aisle. Kellogg owns assets for this moment — Special K Protein, RXBAR — and in these baskets they appear far less often.

The competitive cut
Among the same shoppers, the sweeter, character-driven cereal lineups soften a bit more, while one major player holds roughly steady.
Change in cereal share of basket by manufacturer, before → after GLP-1
Cereal purchases only, as a share of total basket, averaged across shoppers.

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