We eat for many reasons, but the bottom line is that food is fuel for our bodies, so what we eat affects how energetic we feel throughout the day.
Odds are you could use a little more energy.
Here's what you need to know.
Don't run on empty
An energy-optimal meal or snack includes a mix of high-quality carbohydrates for energy with some lean protein and healthy fat for staying power.
Pick slow-digesting carbohydrates ("slow carbs") like whole grains, whole fruits, vegetables or beans for a steadier supply of energy.
It's not just what you eat, but how often you eat that matters. Eating every three to five hours also supports steady energy by encouraging gentle rises in blood sugar (the body's energy source) instead of a few large spikes.
Going too long between meals can leave you running on fumes, and trying to satisfy a raging hunger with a large meal can leave you lethargic while your body works overtime to digest it.
Eating three meals, with snacks if you have a gap of more than five hours between meals, should do it.
What vitamins can, and can't, do for energy
Vitamins and minerals don't give us energy, per se. Energy comes from calories - specifically, calories in the form of glucose, which is found in carbohydrate-containing foods - and from sleep. That said, fuelling yourself with nutrient-rich foods helps your body run optimally and make the most of food energy.
What about claims - on bottles of supplements as well as energy drinks - that the B vitamins, B12 in particular, will boost your energy?
It's true that B vitamins play essential roles in the complex biochemical machinery that releases energy from the food we eat. If you are deficient in B vitamins, it can affect your energy levels. But if you take in more B vitamins than your body can use, you won't become "super energised". Your body will simply excrete the excess in your urine.
To meet your B needs, look to food. The eight B vitamins - thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), B12 and folic acid (folate) - are often found in the same foods. The richest sources are fish, poultry, meat, eggs and dairy products. Leafy green vegetables, lentils, beans, peas and whole grains also have B vitamins. They are added to many cereals and some breads.
Nutritional yeast and brewer's yeast (but not baker's yeast) are other B sources. If you eat a varied diet, you're probably getting enough B vitamins. B12 is only found in animal products, so vegans often need B12 supplements, unless they are eating foods fortified with B12.
Sleep: The other source of energy
Getting enough sleep on a regular basis makes it easier to stick to good nutrition and healthful habits, while making nutritious food choices may improve your sleep.
When you feel tired, you're more likely to reach for caffeine and sugar to boost your energy, which will make it harder for you to sleep well, perpetuating a vicious cycle.
Here are some foods and beverages that can help you sleep easier:
Fish (especially salmon, halibut and tuna), bananas and chickpeas. These foods are rich in vitamin B6, which your body needs to make melatonin, aka the "sleep hormone".
Tart cherry juice. This juice contains phytonutrients that raise melatonin levels. Be sure to choose a pure, unsweetened tart cherry juice that doesn't have other juices mixed in.
Whole grains, nuts and seeds, dark leafy greens and beans. These foods are rich in magnesium, and being deficient in magnesium may make it harder to stay asleep.
Yogurt and kale. Being calcium-deficient may make it harder to fall asleep. Dairy products and green leafy vegetables such as kale and collard greens boast healthy doses of calcium.
Even if you are logging eight hours in bed, are you sleeping well for those hours?
Food and beverage habits could be getting in the way of quality sleep:
Caffeine. Avoid coffee and other sources of caffeine for at least four to six hours before bed. Your tolerance for caffeine after noon may vary.
Alcohol. It's a myth that a nightcap helps you fall asleep. Alcohol starts to act as a stimulant after a few hours, causing you to wake up more often. Keep your daily intake moderate and avoid imbibing within three hours of bedtime.
Night eating. If you must eat a late dinner, keep it light and avoid foods that tend to cause you indigestion. Ideally, eat dinner at least three hours before bed.
If you get hungry before bed, stick to a small, carbohydrate-rich snack, which may help you go to sleep more easily.