There are plenty of weightlifting benefits, including increased strength, better stability and improved stamina. Fat loss may not be the first benefit to pop into your head. However, lifting heavy on a calorie deficit is not only possible, it's important if you want to keep your hard-earned muscle and strength.
Learn what happens when you lift weights for weight loss and why strength training can (and should) fit pretty smoothly into your weight loss diet plan.
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Weight Training on a Calorie Deficit
To lose weight, you have to create a calorie deficit, which means you must eat fewer calories than you burn. You can achieve a calorie deficit through diet, exercise or both. But in order to gain muscle, you need to eat in a calorie surplus, which means eating more calories than it takes to maintain your weight.
It may seem like gaining strength while in a calorie deficit is impossible or counterproductive — well, it's not but it can be challenging, according to Carolina Araujo, CPT, a New York-based strength coach.
Is It Good to Work Out on a Calorie Deficit?
If you decide to eat less to achieve a calorie deficit, it will work as long as you're actually taking in fewer calories than you're burning. To figure out how many calories you need each day, use a calorie tracking app, which gives you an estimate of how many calories you should eat when you want to lose weight. You can also log your food and track your daily calorie intake.
Exercising to achieve a calorie deficit is more complicated but can help you lose weight more quickly.. It's hard to track how many calories you burn in a workout because there are many factors involved, including your training intensity and your body size. Plus, weight training builds muscle and helps you lose body fat (more on that below) but it doesn't spike your heart rate as much as other exercises.
Combining exercise and diet seems to be the best method, particularly if you lift weights or do body-weight strength exercises.
Is It Harder to Build Muscle in a Calorie Deficit?
While you might feel lighter on a calorie deficit from eating less and losing weight, you may struggle to hit record numbers. Your can increase your performance in the gym but it can feel difficult without extra energy.
Your weightlifting routine doesn't necessarily need to change if you're in a calorie deficit, Araujo says. You can continue whatever program you were already on but if gaining strength is your goal, you would still need to train with progressive overload (increasing your weight, reps or sets over time).
"Progressive overload in a calorie deficit is possible but it's more challenging with lower calories," Araujo says. "Since you're in a deficit, your body should, theoretically, pull from its fat stores for energy."
Why Am I Not Losing Weight in a Calorie Deficit, while Lifting Weights?
Lifting weights helps you gain muscle and improve your metabolism, which benefits your overall body composition (your body's ratio of fat to muscle), according to the Mayo Clinic. But body fat and weight aren't the same thing. Body fat has weight but the number on the scale reflects body fat, muscle, bone and all the other parts of your body.
In addition to fat loss, strength training can also help you gain muscle. But muscle also has weight and is actually more dense than body fat, according to Araujo. Muscle takes up less space than fat, too.
"Since muscle is more dense than fat and takes up less volume, you may look smaller and leaner but your weight maybe stays the same," she says.
That's why it's probably more productive to aim for fat loss, rather than weight loss. So, if it seems like you're not losing weight while strength training in a calorie deficit but the number stays the same, it's because you're actually gaining muscle, while losing fat.
Lifting Weights to Preserve Muscle Mass
When you're in a deficit and exercising, your body starts to use its own tissues for energy. Unfortunately, this often means your muscle mass starts to decrease. But lifting weights while in a calorie deficit can also help you maintain lean mass.
An April 2018 research review published in Nutrients found that lifting weights preserved roughly 93 percent of muscle mass in subjects who were dieting to lose weight. The subjects lifted weights three times per week and consumed only 15 percent of their calories from protein, which is low for a calorie deficit.
The results indicate that lifting weights can preserve muscle mass during a caloric deficit — even if you don't increase your protein intake. The subjects still lost body fat, while preserving muscle.
A separate study examining the same question had the same findings. In January 2018, the study was published in Human Kinetics and had three groups of subjects: no change, diet only and diet plus weightlifting.
The weightlifting group actually gained muscle, even though they were on a diet. However, they were given 3.1 grams of protein per kilogram of body weight per day, which is a high amount and helps build muscle.
Why Am I Lifting Heavier but Losing Weight?
Although lifting weights can help preserve your muscle mass, a high calorie deficit can start to diminish your hard-earned muscle. But that's where your nutrition (specifically, your protein intake) comes in place.
In your body, protein is broken down into amino acids, which are like building blocks. Your body reassembles those amino acids to build muscle and other tissues, helping you recover after a workout. But if you don't eat enough, your body doesn't have the building blocks needed to repair existing muscle and build new tissues.
The normal recommended intake for protein is 0.8 grams per kilogram of body weight, according to a March 2018 review published in Human Kinetics. However, when you're in a caloric deficit, you may need more protein to prevent muscle loss. You can even gain some muscle while in a caloric deficit, especially if you're new to exercise.
A June 2017 article published in the Journal of the International Society of Sports Nutrition explains that athletes who are in a caloric deficit may need between 2.3 and 3.1 grams of protein per kilogram of body weight to prevent loss of muscle mass. But for the average gym-goer, 3.1 grams of protein is a lot and probably unnecessary. So, you can likely aim for the lower end of that spectrum (see the chart below).
Protein Goals by Bodyweight
Eating more protein can actually make it easier to eat fewer calories. Protein has a satiating effect, which means it keeps you feeling full longer than many other foods that are low in nutrients. A June 2015 review published in the American Journal of Clinical Nutrition showed that eating a higher protein diet reduced appetite and helped subjects manage their weight.
So, it is possible to lose weight while strength training in a calorie deficit and even increase your lean muscle mass. However, aiming for fat loss, rather than total weight, is a better indicator of your progress and overall health. Improving your body composition with consistent, progressive strength training and protein-focused eating habits can help you feel better in and out of the gym (plus, your clothes may fit a little better, too).
- Nutrients: "Resistance Training Prevents Muscle Loss Induced by Caloric Restriction in Obese Elderly Individuals: A Systematic Review and Meta-Analysis"
- Human Kinetics: "Resistance Training Combined With Diet Decreases Body Fat While Preserving Lean Mass Independent of Resting Metabolic Rate: A Randomized Trial"
- Human Kinetics: "Protein Recommendations for Weight Loss in Elite Athletes: A Focus on Body Composition and Performance"
- The American Journal of Clinical Nutrition: "The Role of Protein in Weight Loss and Maintenance"
- Food & Function: "Dietary Protein Intake and Human Health"
- Journal of the International Society of Sports Nutrition: "International Society of Sports Nutrition Position Stand: Protein and Exercise"
- Nutrients: "Body Composition Changes in Weight Loss: Strategies and Supplementation for Maintaining Lean Body Mass, a Brief Review"