Yes, undereating can make you feel more tired and sluggish, leading to a desire to sleep more, but it often results in poor quality sleep with restlessness and early waking due to low blood sugar, causing fatigue rather than restful sleep. While some people might sleep more due to general fatigue, prolonged under-eating disrupts sleep cycles, making you feel unrested and draining energy, creating a cycle of fatigue and poor sleep.
Severely calorie-restricted diets have also been shown to be negatively linked to sleep, in both reducing deep sleep patterns and the ability to fall asleep.
When someone is undereating, they are consuming fewer calories than their body needs to function correctly. This can have a severe impact on energy levels, causing feelings of physical tiredness and mental fatigue, which may impair a person's daily functioning.
Why Do I Sleep Better When I Eat Less? The most likely answer is that eating less means your stomach isn't overly full, and that's helping you get better sleep. However, some medical conditions can cause decreased appetite and increased sleep.
There are several symptoms of not eating enough, including food preoccupation and obsession, loss of control around food, amenorrhea (loss of period for more than three months), personality changes like increased irritability, lethargy, and digestive issues like constipation and bloating.
Understanding the 3-3-3 Rule
Specifically, the rule suggests: Three balanced meals per day. Three hours between each meal. Three hours of movement per week.
When caloric intake is insufficient, your energy reserves become depleted, leaving your muscles without the glucose they need for contraction and endurance. This can result in feelings of fatigue and weakness, making even simple physical activities feel like monumental tasks.
The 3-2-1 bedtime method is a simple sleep hygiene strategy: stop eating 3 hours before bed, stop working 2 hours before bed, and stop using screens (phones, tablets, TVs) 1 hour before sleep, helping your body transition to rest by reducing stimulants and digestive load for better sleep quality. A more detailed version adds 10 hours (no caffeine) and 0 (no snoozing) for a 10-3-2-1-0 rule.
Not meeting your daily calories will get your brain into thinking that there is a famine and will signal the rest of your body to slow down in order to save your life. Eating less lowers thyroid activity (pseudo hypothyroidism) down regulating energy levels as well as the desire to move.
The 3-3-3 rule for weight loss is a simple, habit-based method focusing on three key areas: 3 balanced meals a day, 3 bottles (or ~1.5L) of water by 3 PM, and 3 hours of physical activity per week, aiming for consistency over complex diets. It simplifies fat loss by establishing rhythm through consistent eating, adequate hydration to support metabolism, and regular movement, promoting sustainable health without intense calorie counting or restrictive rules, says Five Diamond Fitness and Wellness, Joon Medical Wellness & Aesthetics, and EatingWell.
Eat Smaller Meals More Frequently
It can also help your body understand that you're no longer in “survival mode" and make it feel more manageable to reintroduce extra calories if you're worried about increasing your food intake. Prioritizing protein with these small meals is very important!
The 20-minute rule for eating is a mindful eating strategy suggesting it takes your brain about 20 minutes to receive fullness signals from your stomach, so eating slowly, taking at least 20 minutes for a meal, and waiting 20 minutes before seconds helps prevent overeating by aligning consumption with satiety, reducing unnecessary calories, and improving digestion.
Symptoms of starvation mode
Most research to date indicates that caloric restriction improves sleep outcomes including sleep quality and sleep onset latency. However, the relation between caloric restriction and sleep duration is less clear.
“Everyone's body is different, but for most people, eating less than 1,200 calories a day could slow your metabolism enough to make it harder to lose weight,” says Uy. Some signs you have low metabolism include: Weight loss progress that has slowed down. You feel tired or low energy throughout the day.
If you find yourself having no appetite for a short period of time, it may not be necessary to force yourself to eat. If your loss of appetite is paired with other symptoms of being sick, such as vomiting, forcing yourself to eat may make you feel even worse.
The 2-2-2 weight loss method is a simple strategy focusing on 2 big bottles of water, 2 servings of fruits/veggies, and 2 daily walks, promoting hydration, nutrient intake, and activity to kickstart weight loss, energy, and better sleep, acting as a foundation for healthier habits rather than a complete diet plan. It's easy to follow and encourages movement and nutrient-dense foods but doesn't cover total calorie intake or macronutrients, requiring it to be complemented with a holistic plan for sustainable results.
Being in a calorie deficit and losing weight can lead to hormonal changes, like a decrease in leptin (the satiety or fullness hormone) and an increase in cortisol (the main stress hormone). These hormonal changes might impact your appetite, metabolism, and sleep, which can lead to fatigue.
Hunger is a natural need for food. Common signals of hunger are the feeling of an empty stomach or hunger pangs. Lightheadedness and fatigue can also be signs of hunger.
The koala is famous for sleeping around 20-22 hours a day, which is about 90% of the day, due to their low-energy diet of eucalyptus leaves that requires extensive digestion. Other extremely sleepy animals include the sloth (up to 20 hours) and the brown bat (around 20 hours), with some snakes like the ball python also sleeping up to 23 hours daily.
Our circadian rhythm functions by light and dark cycles and therefore an ideal sleep time is 10pm – 6am give or take ½ an hour either way so a full 8 hours of sleep is achieved each night. Even if you are retired or not working, this is an essential component of good sleeping habits.
Not eating enough foods that have vitamin B-12 and folate can cause vitamin deficiency anemia. Or the body might have trouble taking in and using these vitamins. Without these nutrients, the body makes red blood cells that are too large and don't work well.
Protein deficiency can show up as fatigue, weight loss, and even mood changes. These aren't just "normal signs of aging." They're often red flags that your body isn't getting what it needs to function at its best.
But the common ways that the brain tries to conserve energy and vital nutrients will cause very predictable physical sensations such as chilliness, restlessness, cold hands and feet, poor skin, slowed digestion and digestive pains, slowed heart rate, reduction in essential hormones and poor metabolism.