Here are the conversions:
Fat is 9 calories per gram
Protein is 4 calories per gram
Carbohydrates are 4 calories per gram
As an example, let’s say you have figured out that you need to be eating 2,000 calories per day (I explain how to do this in my previous how to lose/gain weight posts)
Protein. You should eat 1-.5 gram of protein per pound of body weight (2.2-1g/kg). As someone who lifts weights and is concerned with putting on muscle, I eat 1g/lb but the amount of protein you should eat is highly individualized and depends on your goals. Use your discretion. I will go into more detail on this topic in a future post.
Let’s say that you have decided to eat 1g of protein per pound of body weight and you weigh 140 pounds. That means that you should eat 140 grams of protein. If you know you need 140 grams of protein then this means you need to eat 560 calories from protein. To get this I used the conversion factor of 4 calories per gram (140*4=560).
Fat. The recommended fat intake is 25-35% of your daily calories. This number is largely debatable and some people do well on a higher fat diet but for the sake of this example, let’s say you choose to eat 30% of your daily calories as fat. So you take your 2,000 calories and find that you need to eat 600 calories from fat (2000*.30=600). To get grams you use the conversion factor of 9 calories per gram (600/9=66.66). You can round this up to 67 grams of fat.
Carbohydrates. So you have 560 calories from protein and 600 calories from fat. That means that your remaining calories should come from carbohydrates. So you add your protein and fat calories (560+600=1,160) and then subtract that number from 2,000 (2000-1160=840). This 840 calories is the amount of calories you need to eat in carbs. To find that amount of grams use the conversion factor 4 calories per gram (840/4=210). This gives you 210 grams of carbs.
Now you have your macronutrient ratio of 140g of protein, 67g of fat, and 210g of carbs.
Counting your macros gives you the freedom to eat foods that are deemed “unhealthy” or “unclean” by many in the health and fitness industry. I am not telling you to go eat fast food and ice cream everyday though because you also need to be aware of your micronutrient and fiber intake.
Here is a great visual explanation from Andrea Valdez (she is a figure competitor but the information is useful for anyone beginning an exercise program).