How to Lose Weight: Weight Loss Tips Backed By Science

You might be tempted to lose weight fast, but is that the best way?
Published February 4, 2019

It’s hard to resist the allure of quick fixes—especially when it comes to weight loss. But diet plans and weight loss programs that promise rapid or immediate results aren’t sustainable. What’s more, they could take a serious toll on your physical and mental wellbeing. To suss out the difference between weight loss spread over days versus weeks or months and the effects of each, read on:

How fast should you lose weight?

"Losing one to two pounds per week constitutes healthy weight loss,” says Brooklyn-based dietitian Brocha Soloff, RD, CPT. “More than that is too fast.”

According to the Centers for Disease Control and Prevention, pounds taken off gradually are more likely to stay off than pounds shed rapidly. When you drop weight too quickly, you may increase your risk of certain health complications and it often requires high levels of dietary restriction—which can be hard to live with and don’t help you build healthy habits for the long term.

For instance, rapid weight loss can trigger headaches, fatigue, irritability, and constipation, says registered dietitian and strength coach Ben Tzeel, RD, CSCS. Mental fogginess, difficulty concentrating, dizziness, and hormone irregularities can also occur, he adds, blaming lower blood sugar, dehydration, electrolyte imbalances, and hunger hormones that may bubble up in response to an abrupt reduction of nutritional intake. More than a few weeks of intense caloric deprivation can also cause muscle loss, hair loss and gallstones, says Tzeel.

Given the potential for side effects, it’s important to understand exactly how potentially hazardous weight loss diets differ from sustainable weight loss solutions.

Understanding the science behind weight loss

Generally, eating fewer calories than your body burns leads to the loss of body weight, which is typically comprised of a combination of water weight, body fat and “lean tissue” (otherwise known as muscle). But factors unrelated to caloric intake can influence the pace at which your body burns calories:

How diet impacts weight loss

Different eating approaches can lead to different types of weight loss: Diets that elicit rapid weight loss by restricting food groups (think: ones that recommend eating only one or two foods, like the cottage cheese or cabbage soup diet, or the extremely low-carb keto diet)  deliver weight loss because you are eating fewer calories overall. You have fewer food groups to choose from. In addition, restriction of carbs can also encourage the loss of water weight, Soloff says. That’s because the restriction of carbs depletes the body of glucose, it’s most easily accessible source of fuel, forcing the body to tap stores of glycogen—a compound that stores glucose alongside water, Soloff explains. Those water molecules get lopped off and excreted in urine when glycogen is broken down for fuel. What’s more, most rapid weight loss diets scrap foods that promote water retention, like high-sodium options. This causes further loss of water weight through urine, which contributes to this temporary weight loss.

The benefits you derive from any amount of weight loss depend on the extent to which that weight stays off, Soloff says. Repeatedly losing and regaining weight—which is more likely when going on and off of extreme diets—can increase your cardiovascular disease risk, chip away at your psychological well being, and may make sustained weight loss harder.

What metabolism has to do with weight loss

The pace of your metabolism determines how quickly your body turns the food you eat into energy. People with more muscle mass tend to have faster metabolisms. (This is why men, who tend to have more muscle mass than women, also tend to have faster metabolisms and why you may experience weight gain as you age and lose muscle mass.)

Other factors affect your metabolism in addition to sex, including your current weight and height, your activity levels, and your body composition.

How body weight affects weight loss

Body weight is one factor that affects metabolism: the lighter you are, the slower your metabolism and the less energy (i.e., fewer calories) your body needs to function, according to Soloff. This means that as you lose weight, your body’s caloric needs change: You may need to keep adapting your plan throughout your weight loss journey to get the results you want.

How your hormones affect weight loss

Certain hormones also affect how easily you lose weight. Lower levels of thyroid hormones, which control how many calories we burn at rest, can make dropping pounds harder, Tzeel says. It’s why hypothyroidism, a condition in which the thyroid gland doesn't produce enough thyroid hormone, interferes with weight loss. The same goes for other medical conditions that affect hormones involved in metabolism and appetite, like Cushing’s syndrome, polycystic ovarian syndrome, and Addison's disease.

How meal timing affects weight loss

You may have heard that eating late at night may affect weight loss efforts and potentially contribute to heartburn, indigestion, bloating, and gas, according to Chicago, Illinois-based dietitian and advisor to Smart Healthy Living Amanda A. Kostro Miller, RD, LDN. That said, emerging research is conflicting: While eating the bulk of your daily food intake in the form of a large, late-night meal may have negative impacts, night time eating itself might not be as problematic as what and how much you eat. That said, there’s also research on time-restricted eating to suggest eating earlier in the day and fasting for an extended period overnight may improve the appetite hormone ghrelin and increase fat burn, although more research is needed.

How lifestyle factors affect weight loss

Researchers have surfaced a variety of correlations between certain lifestyle factors like screen time and weight: The more time you spend in front of a screen, the greater the odds of being overweight. What’s more, insufficient sleep is correlated with an increased risk of obesity; access to palatable foods can lead to eating more while people who live further from stores that sell healthy food are more likely to be overweight; and your social circle may influence your diet and ultimately affect your weight. Additionally, some medications (like some antidepressants, antipsychotics, and some birth control options) can affect the scale, Soloff says.

Developing and maintaining healthy eating habits

Now that you've wrapped your head around the science of weight loss, it's important to understand the pillars of healthy eating, which can help with weight control. Hint: It's not just about consuming “diet” foods—it’s about being mindful of how and what you eat, and other lifestyle factors that influence your appetite and food decisions.

To achieve healthy eating habits that set you up for optimal health, look beyond counting calories: It’s important to consume an mix of food groups to ensure you get an adequate mix of macronutrients (fat, carbohydrates, and protein) and micronutrients (vitamins and minerals), says Kostro Miller. You’ll tick that box by eating a diverse array of fruits, vegetables, lean proteins (like fish, chicken, low-fat dairy products, and soy), healthy fats (think: nuts, avocados, and olive oil), and whole grains (like oats, brown rice, bulgar, quinoa, and more).

It’s also important to lower your intake of saturated fat, added sugars, and sodium, which can reduce your risk of adverse health outcomes (like diabetes, high blood pressure, obesity, and heart disease).

As per U.S. Dietary Guidelines, women should aim for at least 25 grams of fiber, 1.5 to 2 cups of fruits and 2 to 2.5 cups of vegetables per day while men should aim for 38 grams of fiber, 2 cups of fruit and 2.5 to 3 cups of vegetables per day. The American Heart Association (AHA) advises women to cap their daily intake of added sugars at 25 grams (or 6 teaspoons) and men to cap theirs at 36 grams (or 9 teaspoons), while the USDA/DHHS is (slightly) more liberal, recommending that you cap total added sugar intake to 10% (about 200 calories of sweets on a 2,000 calorie diet). The AHA also advises limiting saturated fat intake to 5 to 6% of total daily calories (USDA also recommends keeping this under 10% of total calories). One gram of fat equals 9 calories; if you’re consuming a 2,000-calorie diet, that would mean about 13-22 grams max.

Other secrets of healthy eating? “Having regular meal times so you don’t become ravenous and end up overeating,” Kostro Miller says. “And minimizing mindless snacking or eating out of boredom.” If your tummy’s rumbling after dinner, choose smaller snacks of healthy fats, lean proteins, or fiber, she advises.

The value of regular exercise

Regular physical activity is another critical component of healthy weight loss: While 2019 research published in The American Journal of Clinical Nutrition demonstrates that dietary changes are even more important than exercise in promoting measurable weight loss, a combination of diet and exercise has been shown to work best. Combined with a healthier diet, increasing physical activity can lead to 20% greater weight loss than changing dietary intake alone. What’s more, evidence suggests that regular physical activity can help you keep off weight you've lost.

The science is pretty simple: When you lose weight, your metabolism slows down since your body needs to create less energy to keep your body up and running. Exercise offsets some of these metabolic changes because it helps you build lean muscle mass that amps up your metabolism and contributes an additional caloric burn. That said, exercise alone tends to impact weight loss less than you’d think, The American Journal of Clinical Nutrition research concluded. That’s because it may increase your appetite and/or food intake to compensate for calories burned, which people tend to overestimate.

Striving toward a healthy emotional relationship with food

Have you ever reached for food in response to stress? While you might think this eases your emotions in the moment, practicing this coping mechanism habitually can undermine your wellbeing and interfere with your weight loss efforts in the long term. Recognizing the way you feel and experimenting with other strategies to help you feel better—like calling a friend, listening to music, taking a walk in the fresh air, or jumping in a hot shower—can help you disassociate stress and eating.

At mealtimes, you can shift the way you eat by slowing down and truly savoring your food: Pay attention to the tastes, textures, and aromas; put your fork down between bites; and pace yourself with the slowest eater at the table. This way, you may find you enjoy your meal more and notice how feelings of hunger and satisfaction change with each bite. 

Another way to adjust your relationship with food starts with how you think about it: While you might have heard that certain foods are “good” while others are “bad”—and should be avoided entirely—cognitive behavioral research suggests that categorizing food in this way can actually contribute to overeating in the long run.

Instead, Kostro Miller suggests focusing on the nutrients that food provides: Making a decision about what to eat based on which food has the most fiber, for instance, will lead you to choose the fresh fruit over a processed snack. And if you’re focused on packing in healthy nutrients rather than cutting out foods you “shouldn’t” eat, you might naturally reach for say, a smaller piece of cake after dinner because you feel more satisfied by the time dessert is served.

If you find yourself restricting what you eat, avoiding certain foods, feeling deprived, or overeating at the end of the day, and struggle to find a more balanced way of thinking about food, talking to a trusted friend or medical professional may help.

Is the fastest way to lose weight the best way?

Highly restrictive diets may cause rapid weight loss. But that weight loss may not be sustainable because of the extreme habits you need to practice to achieve and maintain results. What’s more, it could lead to adverse health outcomes and set you up for unhealthy eating habits.

The nutritional imbalances wrought by some fad diets have been found to lower immunity and potentially increase the risk of high blood pressure, high cholesterol, and gallbladder disease. What’s more, rapid weight-loss diets often invite weight regain once dieters abandon overly restrictive eating habits, leading to a cycle of yo-yo dieting that can mess with your morale.

On the other hand, an approach to weight loss that does not require extreme restriction and leads to a recommended weight loss of 1 to 2 pounds per week can help you build healthy and sustainable eating habits that deliver ample nutrients from a range of food groups and help you achieve optimal health.

5 weight loss tips for getting started

Losing weight doesn’t have to feel like self-punishment. Consider these research-backed techniques to lower the number on the scale while developing healthy and sustainable habits.

1. Keep smarter snacks at the ready.

If you're craving a snack you'll likely go for what's convenient, regardless of your preference. When researchers offered undergraduates both popcorn and apples in a 2014 study, participants ate whatever was nearest them. Those closest to fruit consumed roughly 2.5 times fewer calories than those closest to popcorn. To emulate this experiment, stock your desk, office fridge, or bag with healthy snacks like fruits or veggies, and add some lean protein (like part-skim cheese) to make these nutritional powerhouses more satisfying.

2. Drink plenty of water.

Staying hydrated is essential for life and health. Drinking more water does not aid weight loss in and of itself—but switching from beverages that contain calories (like regular soda, sweetened coffee drinks, and fruit juices) to calorie-free alternatives (like water and unsweetened tea or coffee) could help you achieve your weight-management goals. To that point: Despite what you might have heard about special waters, there’s no evidence to suggest that choosing one over the other will impact your weight loss efforts or overall health.

3. Indulge consciously. 

You can live a healthy lifestyle and still enjoy what you eat! One approach is to give yourself a choice between foods you enjoy. For example, think: “Tonight, I’m choosing to have a glass of wine instead of dessert,” or vice versa. Being in the decision making seat is more empowering than feeling like you’re policing yourself.

This either/or approach also works for decisions beyond alcohol and dessert. Think: “I’m in the mood to veg out and watch TV. So I’ll either stream a show on the elliptical or I’ll take a fifteen minute walk before tuning in.”

4. Choose “whole” foods over processed foods.

Processed foods often contain added sugars, sodium, trans fats, and other ingredients that can contribute to the calories and impact your health. On the other hand, whole foods tend to contain less sodium and more fiber, nutrients, and satiating unsaturated fats. What’s more, some research suggests, whole grains in particular may speed up your metabolism, says Nicole Avena, Ph.D., visiting professor of health psychology at Princeton University and author of Why Diets Fail. This could explain the association between whole grain consumption and reduced body weight.

So what is a processed food? “Think: Roasted potatoes over potato chips; oranges over orange juice; peanut butter vs. a peanut butter-flavored protein bar; whole grains over refined grains, etc.,” says registered dietitian Jackie London, CDN, the head of nutrition and wellness at WeightWatchers®. “The closer a food is to its natural state, the more likely it is to contain more nutrients—and be more satisfying—for you.”

5. Eat plenty of fiber.

Yes, dietary fiber can aid bowel movements and alleviate constipation. But it has also been found to help regulate blood sugar, boost heart health, potentially increase longevity, and lower cancer risk. It also helps keep you fuller for longer, Avena adds, which can help moderate our caloric intake. 

Foods that are particularly rich in fiber include chia seeds, popcorn, oats, raspberries, pears, artichokes, lentils, green peas, kidney beans and chickpeas, brussels sprouts, broccoli, and red cabbage, Avena says.

5 weight loss tips to keep you on track

An irksome challenge for people trying to lose weight is the dreaded weight loss plateau—when progress grinds to a halt due to changes in your behaviors, food choices, or activity levels. Alternatively, a plateau can result from lack of change: As you lose weight, your body needs fewer calories. Fail to adjust your intake, and you may notice your weight loss stalling.

Here are five practices to consider:

1. Engage in more exercise and physical activity.

Staying active helps burn calories, build strength, and improve heart, bone, and brain health, Tzeel says.

The Office of Disease Prevention and Health Promotion recommends 150 minutes of moderate exercise or 75 minutes of vigorous exercise per week, plus strength training on two days. And try not to skimp on the strength training: Maintaining or increasing your muscle mass by lifting weights (or your own body weight with exercises such as squats and push-ups) delivers a mild metabolic boost.

Short on time? Multitasking can often be a game-changer: “Listening to a book, podcast, or music you love can be inspiring enough to get you to keep walking on the treadmill or take another lap around the block just to finish a chapter,” London says. “Ultimately, incorporating more movement more often into your daily routine is what will help you make healthier habits more consistently—and help you feel more confident about finding new ways to do so within your current day-to-day.”

If you really can't reach the recommended movement benchmarks, cut yourself some slack. Recent physical activity guidelines make it clear that some exercise is better than none—meaning five minutes of walking here and one flight of steps there can benefit your body. Just start where you are today.

2. Connect with others.

Fostering ties with others working towards wellness goals can help you stay inspired. Studies show that we tend to have similar health behaviors to the people who we spend the most time with. So consider opening up your circle to even more people who make health and wellness a priority—and leaning on those who encourage your efforts. Online communities and in-person workshops, exercise classes and walking groups are great ways to widen your healthy social network—get creative. Maybe an active coworker can be your new hiking partner.

3. Seek out healthy foods that fill you up.

Some foods make you feel fuller than others—typically, those rich in lean protein (like fish and poultry), fiber (vegetables, legumes, fruits, and whole grains), or water (fruits and veggies), can support weight loss goals by filling your belly without overloading you with excess calories, Avena says. They can also provide more vitamins and minerals than less-filling foods, like chips, baked goods, processed meats and cheeses, or sugar-sweetened beverages.

4. Reassess your eating habits—and learn as you go.

New habits can take a while (and a lot of repetition) to become second nature—so it’s natural that old patterns can crop up from time to time. Taking a vacation, having house guests, starting a new job, or just experiencing regular old stress can interrupt your routines—it’s completely normal.

If you get off track, reflect on your original approach: Maybe it was too restrictive or void of foods you truly enjoy, your original meal-prep plan was too ambitious for your schedule, or you lost sight of what you were working toward and why. Revisiting your goals and values could give you the jump start that gets you back on track. Next time around, use what you’ve learned about what works best to set one small goal you can accomplish over the next week—and start building some momentum!

5. Give yourself the credit you deserve.

Reflecting on strides you’ve already made—mastering a new healthy recipe, say, or feeling less winded when you walk uphill—is a great way to stay inspired as you work toward your goals. How about other lifestyle adjustments you’ve made—like quitting smoking, spending more time in nature, or finding ways to reduce stress? Building confidence in what you can accomplish and strengthening your belief in your ability to make positive changes to your lifestyle can help you persevere through challenges.

Finding the best approach to weight loss and wellness

Wellness is a long-term life goal. But that doesn’t mean you can’t see—and feel—its results immediately. Making incremental changes can be a source of instant empowerment. Developing a better understanding of science-backed, effective wellness programs and learning how to choose these approaches over short-lived, fad diets can boost your self-efficacy, bolster your knowledge of what’s right for your body, and prevent you from being duped by untested approaches that risk impeding your wellness goals.

Eating well, engaging in more physical activity, and cultivating a more mindful relationship with food are skills you can start practicing any time—starting today.


Katherine Schreiber, MFA, LMSW, co-author of The Truth About Exercise Addiction: Understanding the Dark Side of Thinspiration, is a social worker and freelance writer based in New York City. She specializes in working with adults with severe and persistent mental illnesses, like schizophrenia spectrum disorders. Her work has been featured by Psychology Today, Cosmopolitan, Shape, and TIME.

Reviewed by Zoe Griffiths, R.D., and Allison Grupski, PhD, January 2020