Five foods that are breaking your grocery budget

Groceries are a necessity, but a few items in your cart might be accounting for the large number on your receipt.

Filling up the grocery cart last month probably cost slightly more than it used to do, as all six major grocery store food indexes rose in July, CPI data revealed. 

While the overall food index rose just 0.2 percent, some foods are jumping in price faster than others.

So what's really putting a hole in your grocery budget?

Here are 5 categories that are costing you more:

Eggs

Sticker shock in the egg aisle continued last month, with eggs increasing another 3.3 percent following a 18.3 percent surge in June. The worst outbreak of bird flu in decades has hit supply hard, causing prices to skyrocket.

"There's just a rush for egg supply right now. There's a concern there's not enough to go around," said Will Sawyer, vice president of animal protein research at Rabobank, in a phone interview. He estimates about 10 to 15 percent of the table egg supply was lost to the flu.

Bacon and related products

Customers are paying more for bacon and related products—1.9 percent last month after a 1.5 percent increase the month before. Overall though, you're still paying less for the pig this year than last across the board. That's due to oversupply after the Porcine Epidemic Diarrhea virus (PEDv) outbreak hit supplies in 2013 and farmers ramped up supply too much, causing a glut in the market.

"Now producers have recovered, and we have a lot more supply so now prices are below what they were" last year, Sawyer says.

He attributes a rebound in prices in the second quarter to a reduction in hog weight by producers, which in turn has tightened supply somewhat.

Pork chops

This pork cut rose 2.1 percent during July.

The same factors at play in the rise in bacon and related products are also behind the increase in pork chop costs.

Lamb and mutton

This index shot up 2.9 percent.

Sawyer attributes part of the rise in lamb prices to high prices in beef, a substitute good.

"As beef gets more and more expensive, there are a lot of products that could be competitive, and that's true for chicken and pork and that's true for lamb as well," he said.

Butter

An index for butter ticked up 1.7 percent last month as milk prices also rose 1.4 percent.

This article originally seen on CNBC.