In this article, we’re going to talk about a muscle-building diet designed for naturally skinny women who are trying to gain weight. Make no mistake, this isn’t a weight-loss diet. It’s not even a diet for the average woman who wants to become lean and strong. This is a bulking diet, a diet that will help you gain weight. Lean weight, yes, but the scale will still move up.
Now, muscle-building nutrition can be overwhelming at first, especially for beginners. How much should you eat? Which foods are healthy? Why are ketogenic and vegetarian women both healthier than average despite having seemingly contradictory dietary restrictions? Will intermittent fasting help you build muscle more leanly?
Luckily, nutrition can also be pretty simple if you focus on the fundamentals. There are just two factors that make the difference between gaining nothing or gaining half a pound of muscle over the course of the next week. But there are hundreds of things that make the oh-so-small difference between gaining 0.50 or 0.55 pounds of muscle.
This article is designed to help you go from gaining nothing each week to gaining half a pound each week. Keep in mind that building muscle becomes harder and harder as you become more and more advanced, so we recommend learning everything eventually. But there’s plenty of time for that later, once you’re already building muscle.
Right now, though, you just need to worry about the two most important factors: calories and protein.
- Calories: how to gain weight
- Before you eat big, you need to lift big
- How quickly should you gain weight?
- How much protein do you need?
- Make Eating Achievable, Lazy (MEAL)
- Key Takeaways
Calories: how to gain weight
To gain weight, you need to be in a calorie surplus. When you consume fewer calories than your body needs, your body is forced to burn stored energy (fat and muscle) to get the energy it needs. This causes weight loss. However, when you consume more calories than your body needs, your body has a surplus of energy, and that energy can be stored.
- Calorie surplus = weight gain
- Calorie balance = no change in weight
- Calorie deficit = weight loss
So “being in a caloric surplus” simply means “eating enough to gain weight.” This makes weight gain simple. Not easy, but simple: if you’re not gaining weight as quickly as you’d like, you need to increase your calorie intake.
We’re interested in gaining muscle, not just gaining weight, so our goal is to store that extra energy as muscle mass. But before we can do that, we need to ensure that there’s extra energy available to be stored. Without that extra energy, you won’t be able to store anything at all.
When gaining weight under normal conditions, women generally gain around 60–70% of that weight as fat. So if you gain twenty pounds while eating a regular diet and doing regular exercise (e.g. cardio), then you’ll gain something like 7 pounds of muscle and 13 pounds of fat. That will help you become stronger and more muscular, and it explains why overweight women have such strong lower bodies, but that’s not our goal. We want to build muscle leanly. We want you to finish your bulk with a smaller waist than when you started.
The good news is that if you’re new to lifting weights, due to a phenomenon called newbie gains, you may even be able to lose fat while you build muscle. Here’s how much muscle and strength women can expect to gain during their first year of lifting.
Now, to be clear you won’t be able to lose fat while building muscle forever, and you may not even be able to do it now. Here are some examples of women’s weight-gain transformations after a few months of lifting weights. As you can see, some people gain more fat than others. However, regardless of your genetics and circumstances, the vast majority of your gains can probably be lean.
So how do we do this?
Before you eat big, you need to lift big
First, to prime your body for muscle growth you need to be lifting heavy weights. If you don’t want to sign up at a gym you can lift at home with some adjustable dumbbells. Or you could build a simple barbell home gym. You don’t need fancy equipment, but you do need to lift. No other type of exercise even comes close to weightlifting when it comes to building muscle.
How quickly should you gain weight?
Once you’re lifting weights, the next thing we need to consider is how quickly you should be gaining weight. By adjusting how many extra calories you eat, we can control how quickly you gain weight. After lifting weights, the rate that you gain weight is the biggest determinant of how lean your muscle gains will be. The idea is to give your body enough extra nutrients to build muscle, but not so much that the extra extra nutrients are stored as body fat.
The ideal rate of weight gain is going to depend on your genetics, your experience level, and how good your lifting program is. However, for the average naturally skinny woman who’s just starting to lift weights, we recommend gaining about 0.25–0.75 pounds per week. If you gain less weight than that, increase your calorie intake. If you gain more weight than that, reduce your calorie intake.
Now, it takes around 3,500 to gain a pound of body weight, so to gain 0.5 pounds per week, you’ll need to eat around 250 extra calories every day. However, you’ll also be burning calories by lifting weights, and your metabolism will likely get a bit higher as you ease into this bulking routine, so you’ll probably need to eat more extra calories than that. The trick is just to adjust your calorie intake every week depending on how much weight you gain (or don’t gain).
The first week can be a bit of a toss-up. You’re adding in exercise but you’re also adding more food into your digestive system. Sometimes your weight won’t respond in a predictable manner. Don’t read too much into it. And besides, lifting weights will be such a novel stimulus that you’ll probably lose a bit of fat and gain a bit of muscle regardless of your diet.
After the first week, we normally recommend adjusting your calories in 200-calorie increments. So if after your second week of lifting weights, you gain 0 pounds, then add an extra 200 calories. On the other hand, if you gain two pounds, consider removing 200 calories from your diet. Keep adjusting your diet like that as you go along.
This can be a finicky process, but you don’t need to be perfect at it. So long as you’re in the right ballpark, things will go just fine. Your weight gain won’t be steady, but we want to see a steady trend upwards. (You should also notice that you’re getting stronger each week.)
Okay, now, let’s talk about how to determine your calorie needs. There are two ways to calculate how many calories you need:
- Taking your diet as it is now and adding in the calorie surplus on top.
- Starting from scratch and calculating your body’s ideal calorie needs.
Let’s go over the pros and cons of both methods.
Method one: adding calories
With this method, we assume that you’re eating enough calories to maintain your bodyweight, and we add in extra calories on top. As we covered above, gaining half a pound of muscle per week requires roughly 1,750 extra calories per week. So if you’re aiming to gain half a pound per week, just add 200–300 calories per day.
After a week, step on the scale, see how you did, and adjust your calorie intake as needed. Again, adjust in 200-calorie increments every week.
This option is simple and effective, but it only works if you already have a very consistent diet. If you wake up in the morning and have breakfast, bring a packed lunch to work, and then come home and eat dinner with your family, for example. In this case, since you know exactly what you normally do, it’s very easy to strategically add in extra calories without changing your regular routine.
The whole method relies on the fact that you eat consistent meals and serving sizes, though. If you add in a snack between breakfast and lunch, but then that causes you to serve yourself a smaller dinner, this method won’t work. You need to be able to keep your diet consistent, adding in calories on top of that.
The ways that your body maintains your weight can be quite sneaky, too. Let’s say you make a sugary Starbuck’s run twice a week to satisfy some cravings. Or maybe you order takeout once a week. Whatever. Now that you’re adding calories into your diet, those cravings may disappear. But by removing those calorie infusions, you’ll fail to get into a calorie surplus.
Since your appetite will naturally cue you to eat enough to maintain your weight, these subconsciously caloric adjustments are very common.
Now, the diet is self-correcting. If every week you’re adding in another 200 calories, then eventually you’ll start consistently gaining weight. So long as your diet has some structure to it, this method will eventually start to work.
If your diet is too sporadic, though, option number two is better.
Method two: tracking calories
This option is best if you want to build a bulking diet from scratch. The goal here is still to develop a fairly consistent routine, though, so that you can eventually switch back to option #1. Counting calories every day isn’t a sustainable practice for most of us. That’s more something that people do when fitness is their day job.
Furthermore, your digestive system has a rhythm to it. If you eat meals at the same time every day, your digestive system will prepare for them. On the other hand, if you eat sporadically, then you may be dumping food into a digestive system that isn’t ready for it. That’s not the end of the world for most people, but naturally skinny women have notoriously fussy digestive systems, and eating a bulking diet is already hard enough on it. We want to do everything we can do make this diet easy to digest.
Anyway, calorie algorithms can get complicated because so many factors need to be considered. Fortunately, we write to a particular niche of women who share the same specific goal: building muscle and gaining weight.
For the average naturally thin woman eating a balanced diet with a moderate protein intake and doing around three hours of weight training per week, this calorie intake should get you very close to your maintenance calorie needs:
- Maintenance Calories = weight (pounds) x 13
Then adjust a little based on your lifestyle:
- If you wake up, drive to work and sit at a desk all day, decrease the multiplier (13) by 1, making it 12.
- For every extra hour of relatively intense exercise that you do during the week—in addition to your bulking workouts—add an extra 1 to the multiplier. This includes sports and other activities, but not low intensity stuff like yoga or casually biking to work. For example, if you play two soccer games every week, each lasting about an hour, your multiplier would be 15.
This should roughly reflect what you’re already eating. It won’t be perfect, but it’s a good educated guess. If the number seems way off, feel free to adjust it up or down a further 10%. Metabolisms vary from person to person, and chances are that you already know whether yours is larger or smaller than average. My metabolism is Hellish furnace, so I need to eat a little more than most people. As a naturally skinny woman, you may be in that same bony boat.
Now we just need to add in the calorie surplus. Just like with option #1, this means adding 200–300 calories per day on top of your maintenance needs.
Examples of adding calories to your diet
- Increase three meals by 100 calories each. Perhaps you do that by adding a small glass of milk to your meals. Liquid calories are fairly easy on the appetite, so this should be fairly achievable.
- Add in a couple 150 calorie snacks. Snacks have been shown to instinctively cause people to eat more, and they will allow you to keep your main meals reasonably sized. These snacks could be as simple as a homemade protein bar split in half, a whey protein shake, a handful of trail mix, or a couple pieces of fruit.
- Add in a fourth (or fifth) meal. Maybe a small fruit/protein smoothie, or some muesli cereal with milk and frozen berries, a homemade protein bar, or a store bought one—like a Quest bar. All of these options are quick to prepare and consume, rich in fibre, contain a fruit or vegetable (except for the Quest bar), and contain enough protein to spike muscle protein synthesis.
- Have (more) dessert. If you already eat a pretty healthy diet that’s rich in protein and made up mostly of whole foods, perhaps you could just have a 250-calorie dessert after dinner. Bonus points if you make the dessert yourself.
Adjusting your calorie intake each week
The most important thing about your bulking diet is to adjust it based on whether you’re gaining weight or not. Either method will give you a rough starting point, but everyone is a little different.
To absolutely guarantee that you’re consistently building muscle, you’ll need to track your results and adjust as you go. This will also correct for calorie tracking errors or incorrect calorie estimates. It makes the system self-correcting. This is what’s going to allow you to gain weight consistently, even if your body tends to naturally resistant weight gain.
Weigh yourself each week and see how much your weight has changed. We recommend waking up on Sunday morning, peeing, and then stepping on the scale. This will keep your stomach contents and hydration as consistent as possible for each weigh-in. Then, if you aren’t seeing the weight-gain results that you want, simply add 200 calories to your daily target. Or, if you’re gaining weight too fast, remove 200 calories.
As we mentioned above, the ideal rate of weight gain while bulking for a naturally skinny female beginner is around 0.25–0.75 pounds per week, so you’d adjust your calories up or down to get closer to that pace. 0.25 pounds per week is good if you’re more afraid of gaining fat. 0.75 pounds per week is good if you’re more eager to gain muscle. If you want to take a middling approach, aim for 0.5 pounds.
This is how you absolutely guarantee progress. If something isn’t working, you simply keep adjusting things it until it does. When it comes to gaining weight, your calorie intake is the variable that you want to adjust.
If you finish up a few weeks of weightlifting, you still weigh the same amount, and you’re thinking, “Damn, where’s all my muscle at?” Well you’re just looking for the problem in the wrong place. The recipe is fine, you just need more ingredients—more calories.
How much protein do you need?
Why is protein important for women who are lifting weights?
Weight training will get your body trying to build muscle, getting into a calorie surplus will give you enough energy to gain weight, and consuming enough protein will give your body the building blocks that it needs to construct new muscle tissue. (Muscle is made out of protein.) This is the trifecta of muscle growth: lift enough weight, eat enough calories, and eat enough protein.
How much protein should you eat per day while building muscle?
There are some experimental new studies showing a potential muscle-building benefit to consuming as much as 1.5 grams per pound bodyweight (3.3 grams per kilo), but most research shows that muscle is built optimally with around 0.8–1 gram per pound bodyweight (2.2 grams per kilo). That’s probably more than you eat right now, but it’s actually a pretty modest protein intake compared to what most fitness models eat.
Keep in mind that this is how much protein it takes to build muscle. You don’t need to eat this much protein forever. Muscle doesn’t take much protein to maintain, and in addition to that, over time we become better at digesting and using protein. This is why you’ll sometimes see very muscular people eating far less protein than this. This means that in the future you can reduce your protein intake by quite a bit as well.
However, right now you’re going to be building muscle at a rapid pace while also being rather inefficient at turning that protein into muscle mass. So I would try to stay above that gram per pound.
What are the best protein sources?
There are lots of great protein sources: chicken, fish, milk, yoghurt, cottage cheese, eggs, beans, peas, red meat, grains, soy, pea protein powder, and so on This makes eating enough protein pretty easy if your diet has no restrictions. If your diet does have restrictions though, or eating enough protein is still a struggle, we’d recommend getting some protein powder.
Whey protein is cheaper than chicken, fantastic for building muscle, and quite nutritious. However, there are many great types of protein powders. For example, pea + rice protein powder is great for people who have problems with dairy or prefer avoiding animal products.
Are high-protein diets safe?
Yes, most research shows that diets higher in protein are just as safe as diets that are lower in protein. The only difference is that a diet higher in protein supports a more athletic physique, whereas a diet higher in fruits, grains, veggies and healthy fats supports a more sedentary physique. Even vegan athletes and lifters eat plenty of protein.
How much protein should you have per meal?
Hitting your overall daily protein goal is the most important thing, but splitting up your protein intake somewhat evenly over the course of the day can help, too.
In an ideal world, you’ve have at least 20 grams of protein in every meal, and you’ve have at least three meals per day. (Intermittent fasting is okay for building muscle, but it’s probably not ideal, especially for naturally skinny women.)
For example, if you weigh 130 pounds, then that could be:
- 30 grams of protien with breakfast
- 30 grams with lunch
- 40 grams with dinner
- And a whey protein shake as a snack
That would give you 130 grams of protein with a perfect protein distribution for building muscle. That’s a fairly classic way of structuring a bulking diet, too. However, it might mean that some meals where you don’t typically have much protein (such as breakfast) might need to have some protein added in. For example, my wife started mixing protein powder or yoghurt into her morning smoothies.
Make Eating Achievable, Lazy (MEAL)
This is the muscle-building variant to the KISS acronym that I’ve just now invented. When you’re trying to eat more calories, don’t make things complicated. Your bulking diet doesn’t need to be simple, necessarily. Feel free to eat a fun and varied diet. But your diet does need to be achievable.
If you can avoid restricting things, great. Don’t restrict carbs (or adopt the ketogenic diet) unless you absolutely need to. You don’t even need to cut out sugar (so long as your diet isn’t very high in it).
I know these approaches to nutrition provide simple rules—eat everything except for sugar, or everything except for gluten, or everything that a caveman would eat. That makes things simple, and when faced with the overwhelming task of creating a bulking diet, simple can be alluring.
Also keep in mind that most of these food group avoidance things are designed for overweight people who need to restrict their calories in order to get down to a healthy bodyweight. As someone who is trying to gain weight, you need to do the opposite: keep your diet open, keep your diet indulgent, and keep your diet fun.
We generally tend to recommend eating an “anti-diet,” where you intentionally give yourself more freedom to eat the foods that you enjoy, find easier to digest, can afford, and so on. Yes, you should be trying to get most of your calories from whole foods, have some fruit or veggies with most meals, and have protein with most meals. However, you should also be having dessert when you want to, cooking richly flavoured meals that you love, having a drink here and there, and not feeling restricted to chicken salads at restaurants.
You’re trying to gain weight, you’re trying to build muscle, and you’re trying to get strong. This is not a situation where you need to remove easy, delicious sources of calories. This is a situation where you need to expand what you eat. This is about adding nutritious, delicious things into a routine that’s already easy, not time to overhaul everything and start eating totally clean.
If you normally wake up and have coffee and a muffin at Starbucks for breakfast, consider switching that to having a latte, a muffin, and a fruit at Starbucks for breakfast. Your routine is the same and the switch won’t require a ton of willpower. But the milk in the latte adds protein and calories, the fruit adds calories, fibre, phytonutrients and vitamins. This is how you get started bulking—by keeping the changes easy.
That way you can succeed even when you’re feeling lazy, tired, and grumpy.
If you’re a naturally skinny woman who’s trying to gain weight, here’s how you should structure your bulking diet:
- Start by lifting weights, then start eating your bulking diet. Without the lifting, around 67% of the weight you gain will be fat.
- 0.25–0.75 pounds per week is a good pace to be gaining weight as a naturally skinny woman who’s new to lifting weights.
- If your diet is already made up mostly of whole whole foods, is fairly consistent, and your weight stays about the same each week, then you don’t need to count calories. Just add 200–300 calories to what you’re already eating. That will bring you into a small calorie surplus.
- If your diet needs a total overhaul, 13x your bodyweight (in pounds) is probably how much you need to eat to maintain your weight. To begin gaining weight at a good pace, add those 200–300 calories on top of that.
- Weigh yourself each week and adjust up/down in 200 calories increments until you’re consistently gaining weight at your target pace.
- Your weekly caloric surplus is what will determine how much weight you gain that week, but the leanest gains are from small, consistent daily surpluses. Try not to under-eat by 250 calories one day and then make up for it with 500 extra calories the next day.
- Eat 0.8–1 gram of protein per pound bodyweight per day (2.2 grams per kilo).
- Eat the foods you already love—just add more calories and protein.
- Don’t fret about advanced nutrition techniques until this is easy!
If you want a full diet and exercise program that’s designed to help you build muscle and gain weight, you’ll love the Bony to Bombshell Program. It’s packed full of evidence-based appetite hacks, recipes, and sample meal plans that are highly customizable. It also includes all the advanced nutrition techniques that will further accelerate your gains, five months of muscle-building workouts, and a yearlong membership of coaching from us inside the Bombshell community.