Eating when you're physically hungry—as opposed to for any other reason—is beneficial in various ways, says May. You'll consume less food because, rather than eating until the food is gone, your physical satiation cues will tell you when to stop.
So yes, it's OK to ignore beginning signals of hunger such as low energy or a gurgling belly, but you definitely don't want to get to the point where you're so starved you're lightheaded or nauseous, can't concentrate, have a headache, or get hangry.
But if you ignore your body's early hunger cues — perhaps because you're busy, or simply don't trust that you need to eat — or if those cues have gone silent from years of denying them, you may become dizzy, lightheaded, headachy, irritable or unable to focus or concentrate.
However, a lack of appetite is not necessarily a sign that your body has enough food and doesn't need more. It's important to still eat even when you don't feel hungry to make sure you are getting in the required nutrients to become the strongest you there is.
Though stomach growling is commonly heard and associated with hunger and an absence of food in the stomach, it can occur at any time, on an empty or full stomach.
You have a fast metabolism
If your metabolism works overtime, you're probably the envy of all your friends — but as research shows, you're probably almost always hungry, too. That's because the faster your metabolism is, the more you need to eat to feel full.
Specifically, the body burns fat after first exhausting the contents of the digestive tract along with glycogen reserves stored in liver cells and after significant protein loss. After prolonged periods of starvation, the body uses the proteins within muscle tissue as a fuel source, which results in muscle mass loss.
Although you may feel hungry when you are trying to lose weight, and restrict your energy intake, being hungry doesn't mean that you're burning fat, because you can shed pounds without always feeling hungry. The main factor that affects this is the means of how you are losing weight.
Fat burning typically begins after approximately 12 hours of fasting and escalates between 16 and 24 hours of fasting.
As mentioned above, our bodies' natural rhythms become off-balance when we ignore hunger for too long. When people skip meals, their metabolism slows down, which can actually cause weight gain.
A slow metabolism has many symptoms, and you're likely to have one if you find it difficult to lose weight and easy to gain weight. Other symptoms include fatigue, poor digestion, constipation, low mood, and a colder than average body temperature. All of these are caused by the lower production of energy and heat.
Fat-burning ingredients like protein, spicy peppers and green tea have been proven to bump up metabolism. Eat some form of these foods, especially protein, at every meal. Protein is especially important: It takes more calories to digest than other foods and also helps the body build fat-burning lean muscle tissue.
After about a month and a half of eating smaller meals more frequently, you'll naturally feel full with less food, and your body will send signals to stop eating sooner (although Gross says it's unclear if the size of your stomach itself can change—we're talking stretch).
Your intestines are always working to move food and air through your body. You're more likely to hear sounds when you're hungry because there's no food in the intestines to muffle the noise. So there you have it—when you hear stomach grumbles, it just means that there is no food being digested.
While your stomach growling may be something you would prefer to avoid, nothing is really going to happen if you hear them for a bit. You might be perfectly fine simply with occupying yourself and waiting for them to pass.
Your metabolic rate does change during your early life, but it plateaus between the ages of 20 and 60, and only decreases by around 1% per year after that.
In the case of Intermittent fasting, skipping your dinner is better and easier. You can have your dinner either early or have a heavy snack and can begin your fasting. Research suggests that fasting in the evening and overnight, then eating early in the morning is the better way to follow this diet to lose weight.
For most people, there are no serious dangers involved in eating one meal a day, other than the discomforts of feeling hungry. That said, there are some risks for people with cardiovascular disease or diabetes. Eating one meal a day can increase your blood pressure and cholesterol.
The one-meal-a-day diet — also known as 23:1 intermittent fasting — may help people lose weight and body fat. However, it can lead to hunger and cravings and may not be suitable for everyone.
When you fast for shorter durations, your body doesn't have enough time to go into ketosis. This means it won't burn stored fat, and there won't be significant weight loss. As one study concluded, a fasting window of 18-19 hours is more effective in terms of weight loss than those between 12-17 hours [11].