How Long Does It Take for Your Body to Adjust to a New Diet?

Being on a diet means lowering your caloric intake and choosing nutritious foods, but it doesn't have to mean that you're always hungry.

If you're feeling hunger during weight loss, you need a little time to adjust to a new meal plan. But if you're constantly hungry on a diet, then it may mean you need to make some adjustments to your plan.

Here, learn about managing diet-related hunger, whether your body gets used to eating fewer calories and how to feel satiated while dieting.

Hunger is a biological mechanism that is designed to keep you alive, according to the Ohio State University Wexner Medical Center (OSUWMC).

Think of it as the fuel gauge on your car that signals you to fuel up before it stops working: Your body needs food to survive, and hunger is its way of telling you to fuel up.

Hunger is a complex process that is regulated by your brain and a number of hormones. Ghrelin — also known as the "hunger hormone" — is one of the key hormones in this mechanism. It signals the hypothalamus in your brain when you're hungry, per Colorado State University.

Symptoms of hunger can vary from person to person and can include the following, per Utah State University:

• A growling stomach
• Lightheadedness
• Difficulty focusing on a task
• Headaches
• Stomach pain

The rumbling stomach, in particular, is caused by a hormone called motilin — which starts contractions in your digestive system to sweep away last bits of undigested food from your GI tract. Those contractions can sometimes cause your stomach to make loud noises, per Colorado State University.

Diets usually mean selectively eating foods to help you achieve your health and fitness goals. Weight-loss diets also typically involve slightly restricting your calorie intake, which can also alter your meal frequency and satiety.

But how long does it take for your stomach to get used to eating less? This answer may be different for everyone.

Diet statistics show it can sometimes take your body a little bit of time to get used to this new plan you're following. Like with sleep, your body also gets used to certain rhythms and habits when it comes to food, per the Centers for Disease Control and Prevention (CDC). It could take days or weeks to adjust to a new diet.

For example, if you usually eat a doughnut during your morning staff meeting, you may crave it even though you've just eaten a full breakfast.

The general rule used to be if you cut your calorie intake by 500 calories per day, you would lose about one pound a week, per the Mayo Clinic. But this may be too drastic of a change for some people, and there's no guarantee you'll lose this exact amount each week. (Weight loss will largely depend on other factors like genetics, metabolism, height and level of physical activity.)

Ultimately, it's important to make sure the diet you're on is giving you enough calories and nutrition for your body to sustain itself. Will the hunger pains go away if you're not getting enough calories per day to meet your body's energy requirements? Maybe not.

Most adults need a minimum of 1,200 to 1,500 calories per day, according to Harvard Health Publishing. Dropping any lower than that can lead to constant hunger (i.e., starvation) and cause you to overeat, per the Mayo Clinic.

If you're working with your doctor or a registered dietitian to lose weight, let them know if you're feeling too hungry while on their prescribed diet. They may need to make adjustments to meet your energy needs.

Reducing your hunger while on a diet may require you to know the different causes and types of hunger (i.e., you may be more than just hungry). These include:

This type of hunger is your body's way of signaling for nutrition, which it needs to grow and maintain normal functioning. This is known as homeostatic hunger, according to a November 2017 study in ‌Expert Review of Endocrinology & Metabolism‌.

Hedonic hunger could be one of the reasons it's hard to control your appetite on a diet. According to a June 2018 study in ‌Obesity Science & Practice,‌ hedonic hunger typically motivates you to eat energy-dense foods that are tastier than they are healthy.

For example, if you feel like eating dessert right after you've eaten a big meal, it's not because your body is running on empty and you need calories for energy. You want to eat that dessert more for pleasure, to satisfy a craving.

It's not uncommon for your body to sometimes mistake thirst for hunger, according to the Polycystic Kidney Disease Foundation.

If you feel hunger from cutting calories, try sipping on some water before eating to see if you're actually thirsty.

Sleep also plays a role in hunger. In fact, a March 2016 study in ‌Sleep‌ found people who didn't get enough sleep tended to feel hungrier and craved more sugary, less nutrient-dense foods.

You may also feel hungry in response to certain stimuli in your environment, like an advertisement with visuals of a big juicy burger or the sight of a vending machine, according to the OSUWMC.

Emotions like anger, loneliness, stress and boredom can sometimes lead to hunger, per the Mayo Clinic, as can certain medications — like antidepressants or diabetes medication, per the OSUWMC.

Bottom line: If you find that you're hungry often, your diet could be a potential cause, but the above factors could play a part, too.

Regularly eating calorie-dense foods (like baked goods, sweets or fried foods) that are lower in nutritional value can disrupt your body's natural hunger and fullness cues and the processes that regulate your appetite.

This happens because certain foods are able to activate the pleasure and reward mechanisms in your brain, causing you to overeat and gain weight, according to a February 2016 study in ‌Advances in Pharmacological Sciences‌.

The best way to reset your hunger and fullness cues is through switching to a more nutritious eating plan that has plenty of fiber- and protein-rich foods. Chances are you may get full faster and eat smaller quantities, according to an April 2018 article in the ‌American Journal of Lifestyle Medicine‌.

Being on a diet can feel challenging, especially if you always feel hungry. Some ways you can stick with your diet without feeling too hungry include:

• Eating several small meals throughout the day
• Keeping nutritious, low-calorie snacks on hand (like fruits or veggies) to eat if you get hungry between meals

If you've already eaten the amount of calories your body needs in a day, you can try to suppress hunger by drinking plenty of water or other calorie-free liquids. This may help you stay full and will prevent dehydration.

You can even try keeping a food journal to help uncover patterns in your eating habits. For example, if you usually eat dinner around 7 p.m. and then get hunger pangs while you're working late at night, it could be because you haven't eaten anything for a few hours.

If you eat too little while on a diet, you can get hunger pangs throughout the day.

In order to avoid feeling too hungry while dieting, you may have to slowly decrease your caloric intake, while focusing on nutritious, filling foods that are high in fiber and protein.

It may take a while for your stomach and appetite levels to adjust, but ultimately, if you're always hungry, it's healthiest to listen to your body and eat something.

And of course, call your doctor if you're unsure about what your "normal" hunger levels should be.