How to bulk: gain muscle without gaining a lot of fat

A "bulk" is a period where you eat a bit more than your body needs, on purpose, so it has the extra energy and material to build muscle. Done well, you gain mostly muscle and a little fat. Done badly (the "eat everything" bulk), you gain mostly fat and spend months cutting it off again.

Here's how to do it well.

Step 1: Find your maintenance calories

Maintenance is the amount you can eat without your weight going up or down. The most reliable way to find it is to track what you eat for two weeks while your weight stays steady. Online calculators give a starting guess, but your real number comes from your own logs and your scale.

Step 2: Add a small surplus

You don't need a huge surplus. Your body can only build muscle so fast, and extra energy beyond that mostly gets stored as fat.

• Start with about 250–500 extra calories a day above maintenance.
• Aim to gain about 0.25–0.5% of your body weight per week. For a 70 kg person, that's about 0.2 to 0.35 kg a week, or about 0.75 to 1.5 kg a month.
• Beginners can gain toward the faster end. If you've trained for years, go slower.

Weigh yourself each morning and look at the weekly average. If it isn't moving after two weeks, add about 100–200 calories a day. If it's climbing faster than your target, take a little away.

Step 3: Eat enough protein

Protein is the raw material for muscle. A large review of 49 studies found muscle gains kept improving up to about 1.6 g of protein per kg of body weight per day, with some people benefiting up to around 2.2 g/kg. For a 70 kg person, that's about 112 to 154 g a day, spread across three to five meals.

Once protein is covered, most of your extra calories can come from carbs (rice, oats, potatoes, bread, pasta, fruit). They fuel hard training. Keep fat at a moderate level so there's room for both.

Step 4: Train hard enough to give the food a job

Eating more without lifting just makes you heavier. The training is what tells your body to turn the extra food into muscle.

• Lift weights 3 to 5 times a week, covering every major muscle group.
• Aim for about 10 or more hard sets per muscle per week. A review in the Journal of Sports Sciences found that more weekly sets led to more muscle growth, and 10+ sets did better than under 5.
• Get stronger over time. Add a little weight or an extra rep when you can. This is called progressive overload, and it's the main signal for growth.
• Train close to failure. Most sets should end with only 1 to 3 reps left in the tank.

Step 5: Sleep and be patient

Muscle is built while you recover, not while you train. Aim for 7 to 9 hours of sleep. And expect it to take time: a few months of consistent bulking shows clear progress, not a few weeks.

Clean bulk vs dirty bulk

A lean bulk doesn't mean only eating chicken and broccoli. Treats are fine. It just means keeping the surplus controlled.

If you struggle to eat enough

• Drink some calories: milk, smoothies with oats and peanut butter, or a shake.
• Use calorie-dense foods: nuts, nut butter, olive oil, rice, granola, dried fruit.
• Add one extra snack a day instead of forcing bigger meals.
• Eat on a schedule rather than waiting until you're hungry.

The short version

• Eat 250–500 calories a day above maintenance, and gain 0.25–0.5% of your weight a week.
• Get about 1.6 g of protein per kg of body weight a day.
• Lift 3 to 5 times a week, 10+ hard sets per muscle, and keep getting stronger.
• Sleep 7 to 9 hours, check your weekly average weight, and adjust slowly.

Bulking is a numbers game: enough calories, enough protein, every day. AIMS keeps track of both as you log meals, and its weekly check adjusts your target from your weight trend.