I've lost weight and want to tone up, but I'm terrified of regaining fat. How do I create a fit physique?

• The concept of "toning" is a myth — the "toned" look really means having muscle, and low enough body fat to see that definition.
• It's understandable to be nervous about gaining weight after you've worked hard to lose it, but that needn't be the case.
• The trick is to up your calories to maintenance level, and track, reassess, and adjust accordingly so you get the results you want.
• Ensure you're applying the principle of progressive overload when weight lifting, as this is key for muscle and strength gains.
• Read more Working It Out here.

Dear Rachel,

I've lost 118 pounds over the last year, but I'm trying to tone up. I used to do cardio every day, but now I just do about 10-15 minutes of cardio to get my heart rate up and lift for about 30-50 minutes a day. I'm in a calorie deficit to this day because I'm terrified of gaining weight. What should I do to increase my muscle tone but not regain the weight I've lost?

— Terrified

Dear Terrified,

Firstly, congratulations on your weight loss achievement, particularly because it sounds like you've done it the right way too.

In a world of fad diets, quick fixes, and unsustainable programs, it takes strength to do it properly, take your time, and focus on creating a new lifestyle that will deliver lasting results.

Prioritizing strength training is really important because it ensures you lose fat and not muscle, and you're thus changing your body composition, not just becoming a smaller version of the same body.

As someone who's done the same in the past, I understand the nervousness around transferring to maintenance or even focusing on building muscle — when you've been in a calorie deficit for a while, it can be scary to start eating more for fear of undoing all your progress.

But if you want to build some muscle, which is necessary for the "toned" look (I'm about to break this myth down for you), coming out of a calorie deficit will help. Don't stress.

You cannot 'tone' a muscle

The idea of "toning" is a myth. Muscles can't go from soft to hard or vice versa, they either grow or shrink.

To create the physique that many people call "toned," it essentially comes down to having muscle on your body, and low enough body fat to show off that muscular definition.

When I lost weight, I'd been resistance training for two years already so I had muscle, you just couldn't really see it under my layer of insulation. When I shed some of that fat, people suddenly started commenting on how "toned" I looked.

"When we speak of tone, we are talking about our body looking firm (which is a result of an increase in muscle tissue) as well as defined (which is a result of a low enough body fat percentage) where we can see the shape of the muscles and the absence of 'the jiggle,'" Pete Geracimo, a trainer who has worked with Adele among other stars, told Insider.

"So in all essence of the word, tone = lean. Muscles themselves do not 'firm-up' or 'tone.' They already are toned or else they wouldn't be able to do their jobs," he added.

Transitioning to maintenance level calories is the key

If you want to sculpt a muscular and lean physique, it comes down to building some muscle while keeping your body fat levels down.

Now, this is possible while in a calorie deficit, as personal trainer Ben Carpenter previously explained to me, but it sounds like you may not need or want to lose any more fat, and you'll get better results by upping your calories somewhat.

"Continuing to keep yourself in a calorie deficit is going to backfire eventually," Sohee Lee, certified Strength and Conditioning Specialist, Sports Nutritionist, and author of "Eat. Lift. Thrive." told Insider.

"You don't want to extend the diet phase longer than needed; now is the time you should be fueling yourself adequately and building up your muscle and metabolism. You can't do that when you're not eating enough," Lee added.

"It's common to forget all the benefits that come out of letting yourself eat enough food, including but not limited to: better energy levels, better workouts, increased strength, improved libido, and more mental bandwidth to devote to other areas of your life," she said.

Lee pointed out that coming out of a deficit doesn't mean you'll suddenly "pack on fat." There's a middle ground.

Track, reassess, and be patient

Calorie-tracking isn't for everyone, but it sounds like it's a system that works for you, which is great.

There's no formula for working out exactly how much more you should eat to help you build muscle without gaining lots of fat, so the best thing to do is trial and error, tracking as you go and adjusting as you see fit.

"I would recommend tacking on anywhere between 200-500 calories onto your current intake (depending on how steep of a deficit you're keeping yourself in), then reassessing how you feel and where things are in 2-3 weeks' time," Lee said. "I think you'll be pleasantly surprised that all your progress doesn't unravel just by giving yourself permission to eat enough."

How much you consume is more important than exactly what those foods are, but if you want to go more detailed you can think about your breakdown of macronutrients (AKA macros): proteins, carbs, and fat.

"There are websites and apps that can work out the correct macronutrients you need in order to achieve your specific goal, but usually for a client that wants to stay lean but put on some muscle mass, I would recommend: 25-40% protein, 20-35% fat, 30-40% carbs," Jono Castano, a personal trainer who has recently worked with Rebel Wilson, told Insider.

Bear in mind that building muscle takes a long time, and you need to be patient.

"Some body types are genetically predisposed to building muscle faster and easier than others," Geracimo said.

"But regardless of genetics, it takes a massive effort and time (weeks or months) to put on even one pound of muscle. So we are talking lots of eating and lots of lifting."

Focusing on weight lifting is the right way to go

It sounds like you're on the right track with your resistance-focused workouts.

"The more lean muscle you add from strength training, the greater your BMR [basal metabolic rate] will be, which will result in you burning more total calories and fat at rest," Geracimo said.

However, you need to make sure you're continually challenging the body and applying progressive overload: gradually upping the weights, reps, or sets.

"You need to get uncomfortable in your workouts and give your body a reason to change and become fitter and leaner," Geracimo said. "Varying up your training with strength and cardio sessions will not only stop you from getting bored but will also keep your body guessing and on its toes."

"The moment you get too comfortable and you're not being challenged, your body will go into auto-pilot and this is when you experience plateauing," he added.

For your heart health, it's important to keep up some cardio as you are though.

"Cardio training should be kept to more of a moderate level," Castano said. "If you like to really sweat, a few days of high-intensity interval training is fine, just make sure to add in weight and resistance training at least 3-4 times a week."

At the end of the day, please keep things in perspective: How your body feels is much more important than how it looks, so don't forget to take a step back and appreciate everything your body does for you, and celebrate what you've achieved.

Wishing you well,

Rachel

As a senior lifestyle reporter at Insider and a self-described fitness fanatic with an Association for Nutrition certified nutrition course under her belt, Rachel Hosie is immersed in the wellness scene and here to answer all your burning questions. Whether you're struggling to find the motivation to go for a run, confused about light versus heavy weights, or unsure whether you should be worried about how much sugar is in a mango, Rachel is here to give you the no-nonsense answers and advice you need, with strictly no fad diets in sight.

Rachel has a wealth of experience covering fitness, nutrition, and wellness, and she has the hottest experts at her fingertips. She regularly speaks to some of the world's most knowledgeable and renowned personal trainers, dietitians, and coaches, ensuring she's always up to date with the latest science-backed facts you need to know to live your happiest and healthiest life.

Have a question? Ask Rachel at workingitout@insider.com or fill out this anonymous form. All questions will be published anonymously.

Read more Working It Out:

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• I've gained weight over the past 6 months but haven't changed my lifestyle. What can I do to lose fat?
• I've lost weight by counting calories in the past but always get obsessed. How do I slim down without tracking my food?
• I hated gym class at school and have a negative relationship with exercise as a result. How do I move past this and develop a positive mindset?
• I've stopped losing weight even though I'm exercising regularly and eating healthy. How do I break through the plateau?