General Mills (NYSE:GIS) has been posting some of its best growth metrics in years as the coronavirus pushed the volume of at-home eating to new highs. That favorable selling environment persuaded investors to lift the stock this year on the expectation that the business could see a significant boost at least into 2021.

We'll get some important clues in its quarterly announcement on Sept. 23 as to whether that optimism is well placed. Let's look at the metrics to watch in the company's earnings report.

A young girl eating cereal.

Image source: Getty Images.

Slower growth

General Mills hit an impressive level of organic sales growth as revenue jumped 16% through May compared with roughly flat results in the months preceding the pandemic. That surge reflects temporary factors like the complete shutdown of the restaurant industry and widespread work-from-home policies in many other parts of the economy.

But the snack and prepared-food seller is still set to announce decent growth for the fiscal first quarter that runs through late August and captures more-normal consumer behavior around work and eating out.

Most investors who follow the stock are predicting sales will rise by about 5% this quarter, reflecting weaker gains as people worked through their pantries and shifted spending back toward on-the-go food.

The main question here is whether demand is settling at a fundamentally higher rate than before the pandemic struck. Kroger recently said that its customers are reporting plans to continue eating more meals at home, including breakfast, and General Mills' sales volumes will reflect that shift -- if the company is still winning market share.

Reduced costs

The company was making progress in boosting its profitability before COVID-19, and investors should see continued gains in this arena on Wednesday. Gross profit margin strength will be a testament to its valuable brand and successful innovation record. Look for cost cuts, plus a tilt toward higher-margin products, to amplify those gains.

Operating margin landed at 17.7% of sales at its last quarterly outing, up from 17.3% a year earlier. Management celebrated that win and suggested there's plenty of room for additional gains. "We've demonstrated extraordinary agility to meet the unprecedented increase in demand for food at home and to win across our categories," CEO Jeff Harmening told investors in early July.

What's the new normal?

General Mills might decline to issue a detailed short-term sales outlook given all the volatility in consumer demand and retail spending today. But the company is likely to continue its pre-pandemic streak of improving margins even if growth levels back off. 

The main question for investors is to what extent General Mills can keep the new customers it reached since the start of the pandemic in early March. Many of those shoppers enthusiastically purchased consumer staples like its snacks and prepared foods when the restaurant industry was stressed. Now it's up to General Mills to try to win their continued business as economic and health trends return to normal.