In general, weight loss is a good thing. As the CDC notes, even losing 5–10% of your total body weight can lower blood pressure, bad cholesterol and blood sugar.
However, one downside to weight loss is it often means losing muscle tissue, which not only burns more calories at rest than fat, but also helps give your body shape and functional ability. In fact, you can expect a whopping 20–30% of the weight you lose by cutting calories will come from muscle, according to research published in the American Journal of Clinical Nutrition.
That is, unless you take steps to prevent muscle loss. Here’s what to do to hold onto muscle tissue:
One of the first things you should do if you’re trying to lose fat without compromising existing muscle is boost your daily protein intake.
According to a paper from the International Society of Sports Nutrition (ISSN), increasing your protein intake from the recommended 0.8 grams per kilogram of bodyweight per day (g/kg/day) to 1.2–2.4g/kg/day, while also restricting calories (30–40% reduction), can maximize fat loss while maintaining existing muscle.
As an example, this means a 185-pound person who consumes roughly 101–202 grams of protein per day can theoretically maintain muscle even when cutting overall caloric intake by 30–40%. (Divide your bodyweight by 2.2 to get your weight in kilograms, then multiply by 1.2 and 2.4 to get your daily protein range in grams.)
In fact, increasing protein intake may even help you gain muscle while following a calorie-restricted diet — that is, so long as you’re also lifting weights (more on this shortly).
In a study published in the American Journal of Clinical Nutrition, researchers had 40 overweight young men follow a diet that was either lower in protein (1.2g/kg/day) or higher in protein (2.4g/kg/day), and perform a combination of strength training and HIIT six days per week. Though the two groups consumed different amounts of protein, both followed a hypocaloric (low-calorie) diet that reduced their estimated caloric needs by 40%.
By the end of four weeks, the higher-protein group not only lost more fat than the lower-protein group (10.6 pounds versus 7.7), but they also gained roughly 2.6 pounds of muscle, whereas the lower-protein group added none.
So, how do you go about increasing your protein intake? As with any macronutrient, you’ll want to look to whole-food sources first, and turn to protein supplements if you have trouble meeting your needs. “I’m a fan of supplementation to enhance a fundamentally-sound diet,” says Michael D. Roberts, PhD, associate professor in the School of Kinesiology and director of the Molecular and Applied Sciences Laboratory at Auburn University. As he notes, protein supplements aren’t any better at creating an anabolic (muscle-building) response than other protein sources with a similar amino acid profile (amino acids make up protein), but they may be a more practical option for people who struggle to get adequate protein.
Great whole-food sources of protein include eggs, nuts (walnuts, almonds, cashews), beans (edamame, black, pinto), Greek yogurt, seeds (sunflower, pumpkin), cottage cheese, lentils and meat and seafood (tuna, salmon, beef, turkey).
The ISSN recommends spreading protein intake evenly throughout your day, and aiming to replenish every 3–4 hours.
In addition to boosting your daily protein intake, performing regular resistance exercise can help you maintain — and even gain — muscle while you shed fat.
“[Weight training] is crucial,” Roberts says. “There is plenty of evidence supporting the notion that weight training can preserve muscle during dieting.”
Resistance training breaks your muscles down, which stimulates a process known as muscle protein synthesis (MPS) or the repair of muscles. Provided you have enough protein, this repair process helps your muscles heal — and grow back bigger and stronger.
Research published in the American Journal of Physiology-Endocrinology and Metabolism even shows performing resistance exercise after following a low-calorie diet for five days can stimulate MPS to reach pre-diet levels. And when subjects also ingested 15–30 grams of protein post-exercise, their MPS levels were 16 and 34% greater than their resting level before they started their diet.
A recent review reveals strength training helped elderly obese subjects maintain muscle while following a calorie-restricted diet and losing the same amount of fat as those who didn’t strength train.
If you’re new to strength training, the American College of Sports Medicine recommends starting with 2–3 sessions per week. After six months of consistent work, you have the option to add another weekly session. Prioritize compound movements like squats, deadlifts, chest presses, bent-over rows and shoulder presses.
Cardio exercise (running, cycling, swimming) can certainly help you lose fat (alongside a healthy diet, of course). In fact, according to the authors of a study published in the Journal of Applied Physiology, aerobic training appears to be the best exercise method for losing fat.
Not to mention, cardio activity offers a variety of other health benefits to make it worth your time. Running, for example, may lower your risk of death from heart disease by 45%, according to a long-term study in the Journal of the American College of Cardiology.
Where cardio might get you into trouble is if you take it to the extreme, all in the hopes of shedding fat: “Many folks’ go-to for losing weight is drastically cutting calories and running miles upon miles every day of the week,” Roberts says.
Instead of running yourself ragged — and risking muscle loss in the process — stick to a combined cardio and strength-training approach. Roberts suggests doing cardio and strength training on separate days.
You might also consider doing high-intensity interval training (HIIT) in place of traditional moderate-intensity cardio, as HIIT likely takes less time.