Protein calculator for weight loss and muscle building

Pick your goal, enter your current weight and choose your activity level. The calculator gives you a daily protein range in grams, and that range split over three meals.

It starts from your current weight because that reflects what your body needs today. Your goal and activity level then move the range up or down.

• Lose weight: enough protein to keep your muscle while you lose fat.
• Maintain my weight: enough protein to hold your weight, muscle and energy steady.
• Build muscle: the highest range, to help your muscles recover and grow after training.

The more you move, the more protein your body uses to recover and keep muscle. Pick the level that matches a typical week:

• Sedentary: little or no exercise, mostly sitting during the day.
• Lightly active: gentle movement such as walking or stretching, 1 to 2 days a week.
• Moderately active: brisk walking, cycling or gym sessions, 3 to 5 days a week.
• Very active: structured training or physical work most days of the week.
• Extremely active: hard training every day, often once or twice a day.

If you sit between two levels, choose the closer one. You can change it as your routine changes.

Protein keeps you full for longer and can take the edge off hunger and cravings, which makes eating less easier. Your body also burns more energy digesting protein than it does carbs or fat.

Just as important, protein helps you keep muscle while you lose fat. Muscle burns more energy than fat, even at rest, so keeping it helps your metabolism. This matters most when weight comes off quickly, for example on a GLP-1 medication.

Protein also supports your immune system, hormones and tissue repair, so it does more than help with weight.

Most research points to 1.2 to 1.6 grams of protein per kg of body weight a day while losing weight. For someone who weighs 150 lbs (68 kg), that is about 82 to 109 grams a day.

The general guideline for adults is 0.8 grams per kg, or about 54 grams for the same person. That is enough to avoid a shortfall, but losing weight on that amount makes it harder to keep muscle.

If you lift weights regularly, up to 2 grams per kg can help with recovery. If you eat fewer calories, for example on a GLP-1 medication, the top of the 1.2 to 1.6 range helps protect muscle. Your care team can help you set a target that fits your plan.

It is possible, but unlikely for most healthy adults. Up to about 2 to 2.2 grams per kg a day is considered safe for people with healthy kidneys, and studies at that level have not found harm to the kidneys, liver or bones.

Problems become more likely when intake stays above 3 to 4 grams per kg a day, especially without enough fluids. At that point the extra protein brings no further benefit for weight loss or strength.

If you have kidney disease or another condition that affects how your body handles protein, talk to a healthcare provider before raising your intake. And keep room for carbs, fats, fruit and vegetables: your body needs those too.

Training puts small amounts of stress on your muscles. Protein supplies the amino acids your body uses to repair them, and that repair is what makes them grow stronger.

Enough protein helps you:

• Repair and build muscle after training
• Recover faster, with less soreness
• Get stronger over time
• Keep muscle while eating fewer calories

Around 20 to 40 grams of protein after a strength workout is enough to get the most out of muscle repair.

With regular strength training, 1.6 to 2.2 grams per kg a day supports muscle growth. For someone who weighs 150 lbs (68 kg), that is about 109 to 150 grams a day, at least double the general guideline.

• Beginners and older adults may do best near the top of the range, around 2 to 2.2 grams per kg.
• People who already train regularly can often keep progressing at 1.6 to 1.8 grams per kg.
• When eating fewer calories, the top of the range helps protect muscle.

Spreading protein over the day works better than eating most of it in one meal. Aim for 20 to 40 grams at each meal.

There is no official ratio, and hitting your daily grams matters more than the exact share. As a rough guide:

• To lose fat and keep muscle: about 25 to 30% of your calories. On 1,600 calories a day, that is 400 to 480 calories, or 100 to 120 grams of protein.
• To build muscle: about 15 to 25% of your calories. On 1,600 calories a day, that is 240 to 400 calories, or 60 to 100 grams of protein.

A typical diet gets about 10 to 15% of its calories from protein. Each gram of protein has 4 calories.

For weight loss, lean sources with little fat or added sugar work best. Approximate protein per 100 grams, from the USDA's FoodData Central:

• Chicken breast, cooked, skinless: 31 g
• Turkey breast, cooked, skinless: 30 g
• Salmon, cooked: 22 g
• Eggs, whole, cooked: 13 g
• Edamame, boiled: 11 g
• Tofu, firm: 10 g
• Lentils, cooked: 9 g

A protein-rich snack keeps hunger in check between meals. Some easy options:

• Greek yogurt
• Hard-boiled eggs
• Roasted edamame or chickpeas
• A protein shake or smoothie
• Beef or turkey jerky with few additives
• A small handful of mixed nuts

Check the label for added salt, sugar and saturated fat, which can work against weight loss.

• Have protein at every meal: a palm-sized portion is a good guide.
• Keep quick options ready, such as hard-boiled eggs or tuna packs, for busy days.
• Rotate your sources: lean meat, fish, eggs, beans, tofu, lentils and edamame.
• Top up with small additions, such as protein powder in a smoothie or nuts and seeds on a salad.