What Every Naturally Skinny Woman Needs to Know About Exercise

If you’re a naturally skinny woman who’s trying to build muscle and gain weight, most workout programs aren’t designed for you. Only 3% of people are trying to gain weight, and most of them are men. As a thin woman who wants to bulk up, you’re in such a small minority, and your goals are so diametrically opposed to the average woman’s, that basically everything you read about fitness will be wrong.

Most of women’s workout programs are either oriented around weight loss (everything), improving cardio (such as cycling), or designed to improve flexibility (such as yoga). So you might try the new trendy new workout routine, try harder than everyone else, and you shrink. Shrinking wasn’t what you wanted, but that’s precisely what the program was designed for.

When that used to happen to me, I thought that my genetics were to blame. But our genetics don’t suck. We’re just naturally thin people who are trying to bulk up. We just need a bonafide bulking program that’s actually designed to help us build muscle, gain weight, and build stronger curves.

What does a women’s weight-gain workout look like?

Let’s Talk About Cardio for Thin Women

First of all, let’s define fitness. Fitness can mean a number of things, but in the mainstream media it tends to mean cardiovascular fitness. This is what most workouts are designed to improve.

Now, to be clear, cardio is fantastic for improving our general health. This doesn’t improve your physical appearance, but it improves heart and blood vessel function. Cardio is also a good way of burning calories and losing weight. The problem is, cardio isn’t very good for our muscles. The weight women lose from doing cardio is a mix of both muscle and fat. For the average overweight woman, that might not be a problem. Most overweight women are already quite strong, especially in their lower bodies. However, as a naturally thin woman, cardio won’t help you build muscle.

You may have seen these examples already, but here’s a woman who is probably naturally slim, and has world-class cardiovascular health and muscular endurance:

Female Olympic Marathon Runner

Here’s another woman who also appears to have a naturally thin build. Except in her case, she’s been weight training to develop her strength and power:

Female Olympic Weightlifter

Both bodies are fantastic. They’re both Olympians after all. However, if your goal is to build muscle, you can see that it’s strength and power that you want to train for, not cardiovascular endurance.

I know these are just examples, but they’re representative examples of the research. It doesn’t matter how gruelling your workouts are or how fearsomely your muscles burn with a hellish fire. If the stimulus isn’t heavy enough, it won’t cause you to adapt by becoming bigger and stronger. Even if you ate a great bulking diet while doing cardio, a large portion of that weight gain would be fat.

I realize that this advice doesn’t apply to everyone. For a lot of women out there, they already have all the muscle they want. They just need to chisel off the fat that’s covering it. Sort of like taking a giant rock and chiseling out the Amazon warrior hidden away inside.

There are a lot of reasons why overweight women are already so muscular. To make a long story short, though, gaining weigh causes both fat gain and muscle growth. Even with a completely sedentary lifestyle, gaining ten pounds will usually result in a good 3-4 pounds of muscle along with 6-7 pounds of fat.

Moreover, carrying around that extra bodyweight will make them even more muscular. Going up a flight of stairs while weighing 200 pounds requires quite a lot of lower-body strength. If you weight 100 pounds, imagine going up a flight of stairs while carrying a 100-pound dumbbell. Imagine how good that would be for building muscle in your thighs and butt. And this is what overweight women are doing every single day of their lives. Often several times per day.

Overweight women are already strong. They already have muscular thighs and round butts. For them, getting toned actually does mean getting smaller. They tone by removing the fat on top of their muscles. That reveals that large muscles that are hidden underneath.

For naturally skinny women, though, getting toned means developing more lean muscle mass. On the plus side, we don’t need to worry about losing fat. On the downside, we need to start climbing those stairs with the 100-pound dumbbell.

Furthermore, cardio isn’t all we need for general health. The World Health Organization (WHO) recommends doing at least 150 minutes of cardio and doing at least two strength training workouts every week. So if you’re a naturally skinny woman who’s trying to get bigger, stronger, and curvier, you should technically be doing cardio and strength training.

This advice is confusing for another reason, though. WHO is recommending that women do “strength training,” but strength training has a couple different definitions. Let’s talk about what they mean.

Should skinny women be doing strength training?

In the fitness industry, strength training normally means focusing on the barbell squat, deadlift, and bench press. Strength training is about trying to get stronger in a powerlifting sense. That’s not what the World Health Organization means. They’re talking about training to build muscle and become stronger.

This is an important distinction to make because that type of strength training isn’t the best way to build muscle. Even if your goal is getting stronger, there are better ways to gain general strength.

In this article, we’re going to talk about a type of strength training that satisfies what the World Health Organization is talking about, but it has nothing to do with powerlifting. We could call this a women’s “bulking” routine, or perhaps a “hypertrophy training” routine. You could even call it a women’s bodybuilding routine.

It’s rare enough for women to want to gain weight that there isn’t even a standard name for it. It doesn’t matter what we call it, though. The important thing is that it’s designed to help a naturally thin woman build a stronger, healthier, and curvier physique that’s shaped more like an hourglass.

We’ll simply call it “lifting” or “weight training.” You’re on a site that focuses exclusively on helping naturally thin women build muscle and gain strength. All of the content here should align with your goals.

Should skinny women start with cardio or weight training?

In an ideal world, you’d eventually have a lifestyle that involves both cardio and weight training. However, if you’re currently fairly sedentary, it might make more sense to ease into this a little bit more slowly.

If you had to pick just one type of exercise to help you build muscle, gain strength, improve your appearance, and improve your general health, then you should start by lifting weights. That’s not true for everyone, but if you’re currently fairly skinny, that’s probably true for you.

The good news is that lifting weights will also raise your heart rate, allowing you to make cardiovascular improvements as well. If you do three weight training workouts per week, each lasting about an hour, that will count for about 90 minutes of cardiovascular exercise. That’s more than enough for a beginner to improve their cardiovascular fitness.

However, if you have time to do both types of exercise, the ideal approach would be to eventually follow the World Health Organization’s guidelines, doing at least 150 minutes of cardio and at least two strength training workouts every week.

What’s the best type of lifting for building muscle?

Hypertrophy training (aka bodybuilding, bulking) is the type of exercise designed to build muscle. Hypertrophy training also comes along with a host of other benefits: greater strength, improved fitness, better general health, greater bone density, increased longevity, and even improved cardiovascular health. However, since hypertrophy programs are designed with muscle growth in mind, these other benefits are just byproducts.

With hypertrophy training, you’ll gain a maximum amount of muscle, whereas any cardiovascular improvements will be more moderate. If you wanted to get the full cardiovascular benefits, you’d also want to add in cardio.

The tricky thing is, most of these “bodybuilding” programs are designed for men. As soon as you starting googling about bulking, you’re going to find sites for skinny guys who are trying to build muscle. And perhaps you don’t want to be “bulky” in the first place, so why would you be looking for a “bulking” program?

By that same token, most bodybuilding information is geared at men who want to be bodybuilders. And again, if you aren’t trying to look like a bodybuilder, there can be a big disconnect there.

To be fair, a lot of the information on these sites is perfectly application to women who are trying to build muscle. If you want to build a bigger butt while gaining overall strength, a bodybuilders approach to squatting and deadlifting will be quite good for that. Not perfect, but quite good. Certainly better than weight-loss “toning” workouts marketed towards women.

One way to think about is is that curviness is found on the path to bulkiness. If you gain 10 pounds of muscle, you may wind up looking curvier but still slender:

Before and after photo of a woman's weight gain transformation

Depending on how skinny you’re starting off, you be able to gain even more weight while still looking quite slender:

Before and after photo of a skinny woman's weight gain transformation

Regardless, at a certain point, you’ll build enough muscle that you start to look remarkably strong and curvy. Here’s a good example of that:

Before and after photo of a skinny woman gaining weight and building a bigger butt

Now, what if you kept going? What if you gained 30, 40, 50, pounds? That’s when you might start looking bulky. I’ve personally gained 55 pounds, Marco has gained 63. That has bulked up our physiques quite a bit. Mind you, we’re men, and we’re tall. But keep in mind that it takes quite a lot of muscle to go from being skinny to being bulking. There are many stops along that train gain ride.

If you gain 50 pounds, yeah, maybe you’ll look like a bulky bodybuilder. However you aren’t going to wake up one morning after having gained 20 pounds only to realize that now you’re 50 pounds heavier. You could spend the next year or two working towards gaining 20 pounds, then when you reach your size goals, you stop overeating.

Furthermore, your muscles will eventually reach their genetic limit. There’s only so big that your arms can get. And if you have naturally thin bones and you’re naturally thin, you’re going to keep that bone structure even as you bulk up. (Here’s our article about muscle growth and strength potential for naturally skinny women.)

There’s still an issue with most bodybuilding programs though. Most of them are designed for men, so there’s a lot of extra arm work, a lot of extra chest work, a lot of extra waist bulking work, a lot of extra upper-back work. This is going to cause a disproportionate amount of their muscle growth to be in their upper bodies.

What does a women’s bodybuilding program look like?

Now, don’t get me wrong, women should still do plenty of arm, chest, ab, and upper-back exercises, it’s just that you don’t need all of this extra focus on it. You can do a balance muscle-building routine and then add the extra emphasis where you want it. Maybe you want that extra emphasis in your arms, maybe you want it in your hips—that’s up to you.

For an example, let’s say you’re naturally skinny woman who wants to remain slender, but also wants better muscle definition, more of an hourglass figure, bigger hips, better posture, and more overall strength. Bodybuilding is still the best way to accomplish those goals, you’ll just want a bulking program that has those specific goals in mind.

  • Maybe you do fewer biceps curls—or none at all—so that your arms don’t get much larger. You can build balanced arm size and strength from doing the compound lifts, after all (such as chin-ups).
  • Maybe you avoid doing tons of ab (rectus abdominis) isolation work (like crunches) so that your waist doesn’t grow too much bigger. After all, the heavy compound lifts will naturally strengthen your transverse abdominis muscles, which will help to maintain better posture while cinching your waist in tighter like a corset. Squats, deadlifts. and overhead presses are great for that.
  • Maybe that means doing a lot of glute isolation lifts to build bigger hips and a bigger butt. Maybe you even modify your squat technique for that goal, using a low-bar barbell squat and “sitting back” into it. That’s going to prioritize glute growth over quad growth. Or maybe you want to prioritize thigh growth and postural improvements, so you choose a front squat.
  • Even the way that you overcome plateaus and choose accessory lifts is going to depend on your longterm muscle-building goals. For example, are you going to focus on bringing up muscles that lag behind visually? Or are you going to strengthen the muscles that are limiting your lifting performance? Or a mix of both?

Here’s what a few months of “bulking” can do when the training program is designed with those goals in mind. Aomi did a full-body weight training program to drastically improve her full-body strength and muscle mass, while also adding in some accessory lifts for her hips.

Obviously, every woman is going to have different goals. This is just one example. The point is that you can use a “bulking” routine to accomplish a myriad of different goals.

(This may sound confusing, and it can be. That’s why we designed the Bony to Bombshell Bulking Program. We’ve done all the work done for you, and we also include coaching in the member community, where we can help you customize the workout routine to better suit your own genetics, circumstances, and goals.)

How to build muscle at home

Pretty much every naturally skinny person I’ve ever met—male or female—has found the gym pretty intimidating. And I say this as someone who’s been doing this eight years, with nearly 10,000 clients. I’m no exception to that, either. I was absolutely terrified of going to the gym for the first time.

It’s not that skinny people are cowards, it’s just that the gym seems like a place where people are judged based on the size of their muscles. And we have naturally smaller muscles. If you aren’t confident about the size of your muscles, this makes the gym a very intimidating place. But if you’re too intimidated to go to the gym, how can you ever build bigger muscles? A conundrum, to be sure.

If you do have the courage to get yourself to the gym, you’ll soon learn that the gym isn’t actually all that intimidating. Most people there are kind and welcoming, and the ones who aren’t are often too busy admiring their biceps in the mirror to even notice you.

I didn’t know that, though. So my solution was to gain my first 20 pounds at home. That’s what gave me the confidence to step foot into the gym.

You can build muscle with a simple pair of dumbbells

This is by far the simplest way to build at home. All you need are some heavy adjustable dumbbells that go up to 60–100 pounds and a lifting bench. That’s all you need to do our Bony to Bombshell Program. In fact, you don’t even really need the bench. We have plenty of members who do the program with just two adjustable dumbbells.

When it comes to buying adjustable dumbbells, the fancy option is getting some IronMaster ones. However, you can get simple ones like the ones pictured below. Are they perfect? No. Will they help you gain 20+ pounds of muscle? Absolutely.

How to Build a Simple Home Gym to Build Muscle / Gain Weight / Lift Weights

I used a setup like this for several years while living in a small condo in downtown Toronto. I didn’t have much space, so I’d carry the dumbbells and bench into the living room, do my workout, and then store them in the closet.

You could also build a simple barbell home gym

Nowadays, now that I live in a bigger house with a spare room, I’ve built myself a simple barbell home gym. If you have a spare room or garage, and you have $500–1500 available, this is a great way to build a home gym that you can use for a lifetime.

Here’s how to build a simple barbell home gym.

In the long run, this is cheaper than getting a gym membership. But it can certainly be a large upfront cost, especially if you don’t know yet if you’ll adopt weight training as a longterm habit.

Do lifts that match your experience level

If you’re new to lifting and you start attempting back squats and barbell deadlifts, things are going to get real awkward real quick. To get around the steep learning curve, do lifts that match your experience level. We usually recommend goblet squats  instead of back squats, and dumbbell sumo deadlifts instead of conventional barbell deadlifts.

These variants are easier to learn, you won’t look that awkward doing them, they build just as much muscle, they’re safer, and you don’t need a squat rack.

Also, remember that some bodyweight exercises are just as good as weight training exercises. Bodyweight training in general isn’t very good for building muscle, but some bodyweight exercises, such as push-ups and chin-ups, are absolutely brilliant for gaining size and strength.

Again, though, start with beginner variations. You can ease into push-ups by starting on your knees or by raising your hands up on a bench. And you can ease into chin-ups by jumping up and lowering yourself down, or getting some resistance bands and attaching them to your chin-up bar.

Here’s a full beginner workout.

Key Takeaways

The best way to build muscle as a naturally skinny woman is to lift weights. More specifically, you’ll want to do a hypertrophy program, a bodybuilding program, or a bulking program. These are all terms for workouts that are designed to stimulate muscle growth. Everything else is probably a weight-loss workout in disguise.

You may also want to choose a workout that’s designed specifically for women. There’s no real issue with doing unisex or even men’s workouts, but they probably won’t be designed with your specific goals in mind. Or maybe they are. That’s up to you.

The good news is that the better your muscle-building workout routine is, the more your muscle cells will be doing everything they can to grow as quickly as possible. They’ll be incredibly insulin sensitive, meaning that more of the food you eat will be invested in building muscle, and less stored as fat.

The newer you are to lifting, the more exciting this news is. You may think that your genetics are keeping you skinny, but by optimizing your training for muscle growth, you may actually find that you can grow at an incredibly rapid pace. This is due to a phenomenon called newbie gains, and you can see examples of naturally thin women quickly building muscle here.

A few months from now you might be twice as strong, a dozen pounds heavier, feeling more energetic than ever, and pretty excited about what you’re capable of accomplishing with just weight training and a good bulking diet.

If you ever want a full program that covers absolutely everything you need to know about building muscle, videos of every exercise you’ll need to know, dozens of different weight gain recipes, a vibrant community full of great women with similar goals, and coaching/customization from us throughout the process, check out our Bony to Bombshell Program.

Shane Duquette is the co-founder of Outlift, Bony to Beastly, and Bony to Bombshell, and has a degree in design from York University in Toronto, Canada. He's gained sixty pounds at 11% body fat and has over ten years of experience helping over 10,000 skinny people build muscle, get stronger, and gain weight.