"There’s one guarantee that comes with every new year (other than failed resolutions): the influx of quick-fix, gimmicky ads to lose weight, full of false promises to get “snatched” and before-and-after weight loss transformation narratives masquerading as motivation (you know, like “drop the fat and you’ll completely change your life!”). Whether it’s restricting entire food groups, fad diets and cleanses, super-strict challenges, or medication dupes, the wellness industry has lost the plot: to feel good, prioritize your health, and feel confident in your own skin (ICYMI, your worth and happiness is not dependent on your jeans size). But if the goal of losing weight checks those boxes for you, you must have safe, positive, and genuinely healthy advice to get you there.
To cut through the noise (read: antiquated diet culture and a $90 billion industry), I asked a triple-board certified, leading medical weight loss doctor, Dr. Sue Decotiis, MD, to share her overarching principles on how to approach losing weight to reveal new tips that you may not have heard of. Keep reading for Weight Loss 101–2025 edition.
Dr. Sue Decotiis, MD
Dr. Decotiis is a triple-board certified weight loss doctor, considered one of the best weight loss doctors in New York City. She is an attending physician at NYU Medical Center, where she specializes in medical weight loss.
1. The timing of when you eat matters
You know that what you eat affects your weight, but Dr. Decotiis suggested that when you eat also can help or hinder weight loss goals. A study in Cell Metabolism found that eating late (in this case, 8:30 p.m. compared to 5:30 p.m.) encouraged weight gain (controlling for other variables like caloric intake, physical activity, sleep, and light exposure). More specifically, late eating greatly increased hunger, decreased levels of the appetite-regulating hormone leptin, increased the amount of fat that was stored, and decreased the rate at which calories were burned over the 24-hour day by changing the activity of the genes that control the burning and storage of fat. TL;DR: Eating late (after around 7-8 p.m.) makes you less glucose tolerant and also causes the body to burn less fat than if you had the same food earlier in the day.
2. Don’t skip meals and plan ahead
While many people forgo breakfast, lunch, or dinner in the name of weight loss, it can have the opposite effect they want. “Fasting is not for everyone,” Dr. Decotiis said. “For many people, it can do more harm than good. It can cause muscle loss and overeating when you break the fast.” When you continually skip a meal or go a long time without eating, the body will produce more ghrelin (the hunger hormone) and less leptin (the hormone that regulates appetite), making it harder to distinguish when you’re already full and potentially leading to overeating or binge eating. As a result, weight loss could slow down, and you’ll likely regain body weight as soon as you start eating normally again.
Dr. Decotiis recommended to plan ahead if you’re going into a particularly busy day or week. Meal prep a few healthy recipes and have high-protein snacks at the ready. If you’re especially short on time, pre-wash fruits and vegetables in advance to make it easier for you to incorporate more of them in your diet. Otherwise, when you’re exhausted or in a hurry, you’ll more likely reach for whatever is easiest and most convenient (like packaged food). With a little preparation, making more nutritious food decisions becomes a no-brainer.
3. Have designated food breaks throughout the day
While skipping meals can hinder weight loss goals, Dr. Decotiis also suggested that the body needs breaks in between meals, so keep specific windows of time (such as breakfast from 7 a.m.-8 a.m., lunch around noon, and dinner around 6 p.m.-7 p.m.). “Having specific windows of time to eat is a great way to stabilize your metabolism and ensure that insulin is working the way it’s supposed to,” she said. “Eating throughout the day—whether it’s healthy food or not—will slow down your metabolism.” Every time you eat, the insulin in your body has to start working to regulate blood sugar levels, and when insulin levels rises, it stops burning fat for fuel and encourages storage of incoming food, mostly as fat. Giving insulin “rest” by eating only during mealtimes translates to maintaining insulin levels and cells burning fat more effectively, which can contribute to weight loss.
4. Don’t rely just on working out
You may have heard of workouts intended to burn calories or programs that insist on intense and grueling workouts to lose weight, but exercise may not have as much impact on our weight as we’ve been taught. In fact, Dr. Decotiis suggests that if people overdo their workouts, it may cause them to eat more than they need. A 2017 study confirmed that exercise alone plays a very small role in weight loss. While 100 percent of the energy we gain comes from food, we can only burn about 10 to 30 percent of total energy expenditure with physical activity in a day; to lose weight, you would need an incredibly high volume of exercise to burn enough calories. A review of studies from 2012 found people generally overestimated how much energy they burned through exercise and ate more when they worked out.
While exercise may contribute to weight loss maintenance efforts in the long run, researchers affirm that adding a regular exercise program is unlikely to lead to significant weight loss. There are so many powerful benefits of exercise and reasons you should move daily: increased longevity, improved mood, better energy and sleep, or to prevent chronic pain and injuries–just to name a few. Weight loss is not necessarily one of them. If weight loss is your main health goal, Dr. Decotiis recommended moderate exercise, staying about 70% of your maximum heart rate, as it is the most condusive zone for weight loss (think: brisk walking or light jogging).
5. Remember that trends don’t work
Contrary to the latest breakthrough weight loss trend, Dr. Decotiis insists what we inherently know but sometimes don’t want to believe: these things don’t work. Your weight has to do with incredibly basic, untrendy factors. While genetic influence is estimated at 40 to 70 percent, the remaining factors that contribute to weight are diet, exercise, stress, sleep patterns, and overall lifestyle choices. Dr. Decotiis often sees drastic changes, unsustainable diets, or the latest trends lead to frustration, disappointment, feelings of failure, or even doing the body harm.
6. Eating whole foods really is the only diet you need
Between the carnivore diet, 90/30/50, or plant-based, there are limited diets and eating methods touted as “the best diet for weight loss.” But Dr. Decotiis suggests that the latest fad diet or even a restricting food plan may not be the best option for weight loss (much less sustainable or enjoyable, as food should be). “You want to avoid yo-yo dieting as much as possible–chances are you’re losing more muscle than fat on those diets,” Dr. Decotiis said. She advised that the most reliable starting point for weight loss is simply swapping ultra-processed foods for whole protein and fiber sources. “Typically nutrient-dense food that is high in fiber works well for weight loss,” Dr. Decotiis said. “Always prioritize a lot of vegetables and having protein with every meal.”
As for how much, The Academy of Nutrition and Dietetics recommends .35 grams of protein per pound of body weight for general health. However, if you’re trying to build muscle, are a fairly active individual, or just looking to feel a little more satisfied after every meal, you probably need to aim a little higher (up to one gram per body weight). Adult women need at least 25 grams of fiber daily (and according to the USDA, 95 percent of Americans aren’t eating enough fiber), so get in your fruits and veggies.
7. Patience is key–and think long-term
Our society is inundated with instant gratification, sometimes at the expense of long-term satisfaction–and that goes for weight loss. “Weight loss isn’t about a quick fix; it’s about making lifestyle changes that are sustainable and result in long-term health,” Dr. Decotiis said. She also suggested that people who look for a quick fix or are in a cycle of yo-yoing can lose too much weight, which can have dangerous effects on the body. “For women, rapid weight loss causes your estrogen to drop, which leads to skipped periods, fertility issues, hair loss, and in the worst cases, long-term osteoporosis.”
When it comes to weight loss, gradual and long-term is seemingly the only way to go. A 2020 study in British Journal of Nutrition showed that gradual weight loss is associated with the loss of more pounds of total fat and a lower body fat percentage compared to rapid weight loss. In general, losing about one to two pounds per week is considered sustainable weight loss. “Make realistic goals that are attainable and don’t expect to see results overnight,” Dr. Decotiis said.
8. Weight loss is not always about food and exercise
You’ve probably heard that weight loss is a matter of food plus exercise, or it’s a simple equation of calories in, calories out. In reality, that’s not always the case. The body is much more complicated than a calorie deficit. If you feel like you’re not seeing any results after a few months of positive and healthy lifestyle changes, Dr. Decotiis recommended consulting with a physician. There are many other potential causes you may be gaining or unable to lose weight, such as insulin resistance, hormone-related issues, etc. And find a doctor that will work with you to identify the root cause and find a plan that works best for your lifestyle, goals, and body. “There’s been a lot of negative news coverage on weight loss drugs,” Dr. Decotiis said. “But when it comes to your health, well-being, and quality of life, you need to do what’s best for you and tune out all the chatter.”