As a person's income increases, the proportion of their income that they spend on food (known as the "food share") will typically decrease. This is because as people earn more money, they are able to afford a wider variety of goods and services, and food is often seen as less of a necessity as other expenses such as housing, transportation, and healthcare become more pressing.

However, this does not mean that absolute food costs will decrease as income increases. The absolute amount spent on food may increase with income growth as people are able to afford more expensive, higher-quality foods, and have more options for where to purchase their food (such as buying organic, specialty stores or eating out in restaurants).

Additionally, the way people spends their money on food may change with income as well. Lower-income households are more likely to buy more affordable, staple foods and spend a larger portion of their income on food. While higher-income households tend to buy more expensive, premium food and spend a smaller proportion of their income on food.

There are also other factors that can affect the relationship between income and food spending, such as local food prices, cultural factors, and government policies. For example, households in a country with high food prices and low income may have a higher food share than households in a country with lower food prices and a similar income.

In summary, as income increases, the proportion of income spent on food decreases but the absolute amount spent on food may increase. This, combined with other factors such as location and personal preferences, can impact how spending on food changes with income.