It's a myth that eating at night leads to weight gain, Palinksi-Wade points out; it's more about what you're eating at night that can be an issue when it comes to weight management. "Since most of us don’t have a salad for a midnight snack, if you find you tend to eat calorie-dense, high-sugar foods in the evening (like a bowl of ice cream) setting guidelines as to when to stop eating may help you to lose weight faster."

Difficulty sleeping can be a symptom of menopause, so it's not uncommon for women in their 40s to struggle with getting enough sleep. Unfortunately, this can also cause weight gain. "When you get less than seven hours of restful sleep, metabolic changes occur that can make it significantly harder to lose weight," says Palinksi-Wade. "The appetite hormone ghrelin is increased while leptin (which controls hunger cues) is reduced, triggering an increased desire to eat, especially for foods rich in fat and sugar. Insulin resistance increases, which can trigger the body to store fat."

It’s usually not just due to losing muscle mass over time (more on that later). "It's multifactorial," says Fatima Stanford, MD, MPH, obesity medicine physician scientist at Massachusetts General Hospital and Harvard Medical School. Numerous factors can sneak up on you and help you gain or hold onto weight, including your lifestyle, your food, your biology, and your sleep habits. The good news in that is that there are also numerous ways to tackle getting your weight to where you want it—you don't have to force yourself into one approach, and you get to choose what works for you.