Pound

Definition: A pound is a unit of mass that is used in both the imperial and US customary systems of measurement. Its symbol is lb. The precise weight of the international avoirdupois pound, or today's standard pound, is 0.45359237 kilos. 16 avoirdupois ounces make up an avoirdupois pound.
Gram

Definition: The International System of Units uses the unit of mass known as the gram (symbol: g) (SI). The kilogram, the SI base unit of mass, serves as the basis for the definition of the gram, where a gram equals one thousandth of a kilogram. As of 2019, the definition of the kilogram, along with the revised definitions of the second and meter, is based on Planck's constant, h, rather than the international prototype.

The conversion factor between pounds and grams is:

1 pound = 453.592 grams or 1 lb = 453.592 g

Another way of doing the conversion uses this conversion factor:

1 gram = 0.0022 pounds
The easiest way to convert Pounds to grams is simply multiplying the value in pounds by 453.592. This cancels out the pound unit, leaving grams.
For example, find how many grams are in 0.5 pounds of flour.
grams of flour = 0.5 pounds x 453.592 =  226.796 g or about 227 grams
Also you can know more about converting pounds to calories easily way:
https://www.calculatorful.com/pounds-to-calories-burned