Keto Macros, Net Carbs, and BMR: A Practical Guide Before You Change Your Diet

By CalciTools Editorial · May 30, 2026

Most keto mistakes start with a ratio and skip the person. Saying "eat 70% fat" is not enough. A 5-foot-2 office worker and a 6-foot athlete can both eat a ketogenic diet, but their daily calories, protein target, and electrolyte needs will not be the same.

A better workflow starts with BMR, adjusts for activity, applies a reasonable deficit or surplus, then turns that calorie target into grams of fat, protein, and net carbs.

The basic keto macro pattern

• Fat: roughly 70% to 75% of calories.
• Protein: roughly 20% to 25% of calories.
• Net carbohydrates: roughly 5% to 10% of calories, often under 20 to 50 grams per day.

Net carbs are not the same as total carbs

If a meal has 18 grams of total carbohydrate and 7 grams of fiber, the net-carb count is 11 grams. That number matters because many keto plans track carbohydrate impact rather than total carbohydrate weight.

A worked macro example

Those are planning numbers, not a medical prescription. If you have diabetes, kidney disease, pregnancy, a history of disordered eating, or take medication affected by diet changes, get professional medical guidance before using a ketogenic plan.

Do not ignore electrolytes

When carbohydrate intake drops, many people lose water weight early. That can also shift sodium, potassium, and magnesium needs. This is why some people feel flat or headachy during the first week of low-carb eating even when calories are not too low.

• Track water intake, especially during the first two weeks.
• Use food-first potassium sources where appropriate.
• Do not mega-dose supplements without medical guidance.
• Watch energy, sleep, training performance, and digestion, not only scale weight.