Sports nutrition is easy, if you're a cartoon character. Take Popeye: The gravel-voiced sailorman would down a can of spinach, and next thing he knew he was shot-putting a bowling ball into the stratosphere. Try that at home and the only thing you'll be heaving is the spinach.

"No specific food will make you faster or stronger tomorrow,"says Lonnie Lowery, R.D., Ph.D., an exercise and nutrition scientist at Winona State University, in Minnesota.

Instead, whatever your goal—packing on muscle, going the distance, or losing that gut—you have to think long-term. "Sports nutrition is all about many factors adding up over time." In other words, think marathon, not sprint.

So even though there's nothing that will make you an instant athlete (or substitute for that last set of reps), the right foods and drinks can help you work harder, train longer, and look better. Good nutrition supports good workouts, and good workouts make the most of good nutrition.

We've rounded up the latest research to help you fuel the body you have—and create the body you want. All you need is enough strength to twist a lid, tear a pouch, and, yes, open a can.

Increase Your Endurance
In some ways, your body is one big bundle of fuel wrapped in skin; a man of average size stores enough fat to sustain him for days, weeks, maybe months. So why is it so hard to exercise for much longer than a couple of hours at a time? One word: glycogen.

It's glucose in storage form, and your body's most easily accessible source of energy. You can work, sleep, or wander the mall all day without ever making a dent in the glycogen stored in your muscles and liver. But the minute you ramp it up, your energy supply is on the clock.

"Most adults have enough glycogen to exercise 1 to 3 hours at most. If you're exercising at moderate to high intensity, your glycogen levels will sink more rapidly," says Marie Spano, R.D., a sports nutritionist in Atlanta who works with pro and college athletes.

Your body will never let you use all your glycogen—there's always some in reserve—but you'll start slowing down when the needle nears the E. To train seriously, you need to delay that moment as long as possible.

Load Up and Go Long
Research shows that eating the right amount of carbs several hours before a race or a multihour training session can maximize your glycogen supply, which boosts your endurance.

To top off your tank, your preworkout meal should include 1/2 to 1 gram of carbohydrates per pound of body weight, Spano says. For a 180-pound guy, that's between 350 and 700 calories from carbs (or 2 to 4 cups of cooked spaghetti).

Which end of the range is right for you? Depends on how much time you have to digest. The longer the lag before game time, the more you can eat.

Eat Right for Short Workouts
If you're exercising for an hour or less, you don't need to make special dietary accommodations. But you do need fuel to sustain yourself. Lowery recommends eating a simple meal with at least 200 calories, 20 grams of protein, and 30 grams of carbs an hour or two before your workout. A simple grilled-chicken sandwich will set you up.

Drink for Endurance
Exercise-induced dehydration slows your motor neurons; it's as if you were making Michael Phelps swim through Jell-O. Not only do you feel fatigue sooner than you otherwise would, but your performance slips as well.

Skipping liquids also means missing out on an easy-to-absorb delivery system for the nutrients your body needs during or after exercise.

Knowing how much fluid you need to replace isn't easy. Sweat rates range from a pint an hour to four times that, and of course rates fluctuate with the weather. Whatever you do, don't rely on thirst as a gauge. By the time you're hankering for a drink, you're probably well on your way to dehydration.

There's one way to know for sure if you're drinking enough: Weigh yourself before and after a long race or training session. Almost all the weight you lose is water. Replace each lost pound with 24 ounces (3 cups) of fluid. Another indicator of hydration status is your urine.

If your bladder goes longer than 3 hours without a cry for help, you're probably not drinking enough, Spano says. Color matters, too; urine shouldn't be darker than a pale lager.

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Go Fast for the Burn
If you have to be on the starting line first thing in the morning and your window for digesting food is less than an hour, go for easily digestible carbs with high water content, such as bread (which surprisingly contains 35 percent water), and lower-fiber fruits, like melons and bananas.

Stay away from foods that are high in protein and fat (nuts, for example), which take longer to digest than quick carbs do. Also, avoid high-fiber fruits and vegetables (beans, broccoli, raisins, berries), which can cause gastrointestinal distress if you eat them just prior to strenuous exercise.

Caffeinate a Workout
Caffeine does more than keep you awake. If you're a long-haul athlete, it can boost your performance, help you use more fat for energy (thus sparing your precious glycogen), and reduce post-training pain.

Curiously, though, you can't reap these benefits from the world's most popular caffeine-delivery system.

"There seems to be a compound in coffee that limits caffeine's benefits," says Jay Hoffman, Ph.D., a professor of sports and fitness at the University of Central Florida. That's why caffeine studies that demonstrate its benefits have involved people drinking powdered caffeine dissolved in water instead of consuming coffee.

Energy drinks are another source of caffeine. But they also pack a boatload of calories, and you'd need a Ph.D. in chemistry to decipher their ingredient lists.

Consider taking a caffeine tablet instead so you know what you're consuming. Studies show benefits with 1.4 to 2.7 milligrams of caffeine per pound of body weight, which works out to about 252 mg for a 180-pound guy (maximum-strength No-Doz contains 200 mg). If you aren't a heavy coffee or soda drinker, you'll probably get wired with less.

Add Salt for Stamina
There's plenty of hype about the evils of salt, but avoiding it is bad advice for any man who does high-volume, high-intensity training, especially in heat and humidity.

If you regularly sweat out 2 to 3 percent of your body's weight—3 to 6 pounds, for most of us—you probably need more sodium. Spano recommends SaltStick Capsules (saltstick.com), an electrolyte-replacement product developed by a former pro triathlete. Each capsule has double the sodium of a typical sport drink.

Juice Up Your Body
To protect your muscles during intense training, think dark-red fruit.

A recent study at Oregon Health & Science University showed that runners who drank tart cherry juice for a week before an ultra-endurance challenge had less pain after the race. Tart cherries, red grapes, and pomegranates are all available in juice form, and are loaded with anthocyanins, a type of antioxidant that helps reduce the muscle inflammation and damage caused by serious exercise.

Refuel on the Fly
Along with providing water and carbohydrates, sport drinks replace some of the minerals you lose through heavy sweating.

Three of those minerals—potassium, magnesium, and chloride—are called electrolytes for a simple reason: Your body needs them to transmit electrical signals from your brain to your muscles. Those signals travel through your body's fluids, which are regulated by another electrolyte, sodium.

If you'll be running or riding continuously for longer than an hour, start replenishing your carbohydrate and electrolyte stores around the 30-minute mark, and every 15 minutes after that, Spano says. You want 30 to 60 grams of carbs for every hour of exertion.

So if you tank up with 4 ounces of a sport drink (which usually has about 7 grams of carbs) at 1/4-hour intervals, you'll reach the low end of that range. Eight ounces every 15 minutes and you'll be at the high end.

Feed Your Muscles
Imagine living in a house that's constantly under construction. That's what it's like inside your body, where three shifts of molecular laborers tear down and build up muscle tissue all day, every day.

After strength training, your body's construction crew wants to work overtime, but it needs the right building materials.

"Consume protein as soon as possible after strength exercise," says Stuart Phillips, Ph.D., a professor of kinesiology at McMaster University, in Ontario. If you eat nothing, your muscle growth will be seriously hampered—you could even lose muscle, in fact. Be strategic with foods and supplements instead, and you'll reap big results from your workout.

Whey to Grow
When it comes to muscle growth, one protein source stands out. "Whey protein offers the biggest benefit," Phillips says.

You digest it more quickly than other types of protein, so it hits your muscles faster. Whey protein also has the highest concentration of the amino acid leucine, giving it more muscle-building power than anything in the supermarket. Phillips recommends 25 grams of whey protein postworkout. There's no harm in having more, but there's no proven benefit, either.

Combine Protein with Carbs
Together, they achieve more than either does on its own. Carbs may help protein reach your muscles faster, speeding growth.

Meanwhile, some research suggests protein accelerates the buildup of glycogen. Even if you're on a low-carb diet, you should take in some carbs with your postworkout protein. Use a protein supplement that contains carbs, or add your own with whole fruit. Mix some in a blender with water and ice for the perfect postworkout treat.

You can also use skim milk instead of a protein supplement—24 ounces (3 cups) provides 25 grams of protein, 35 grams of carbs, and a generous dose of muscle-building leucine.

Hit the Right Ratio
For men who run, lift, or play sports a few hours a week, no postworkout combination of carbs and protein has been shown to work better than any other.

But if you're a serious athlete who trains hard for over an hour every day, your best results will come with a ratio of carbs to protein that's at least two to one, some research has shown. Two supplements that are specially formulated to hit this ratio are Gatorade's G Series Pro 03 Recover (for runners, elite athletes, and aspiring professional athletes) and Biotest's Surge Recovery (for serious lifters).

Pop the Muscle Vitamin
Back in the day, fitness buffs were really into the benefits of sunlight: Charles Atlas, for example, included daily sun baths in his famous Dynamic Tension program.

Today, science is starting to figure out what old-school bodybuilders understood intuitively: Vitamin D, created by your body through direct sun exposure without sunscreen protection, has an important role in muscle health and function.

Nobody can say for certain whether vitamin D boosts performance in healthy, fit men; the strongest research involves only the very young and the very old. But giving your body more D (through supplements and/or sun exposure) can't hurt, and it could very well help you grow stronger and avoid injury.

Researchers at the University of Wyoming say most people would benefit from taking a supplement with 1,000 to 2,000 international units (IU) of vitamin D each day.

Don't Lift Dehydrated
Weight training doesn't cause dehydration; after all, lifters tend to work out in air-conditioned gyms. But if you're dehydrated before a lifting session, you could do more harm than good.

A 2008 study in the Journal of Applied Physiology found that dehydrated lifters produced more stress hormones, including cortisol, while reducing the release of testosterone, the body's best muscle builder. If you lift first thing in the morning, have a glass of water first. This is especially important if you're dehydrated from the night before.

Boost Your Results
If you're looking to increase your strength and workout capacity by as much as 10 percent and add muscle size over time, you can't go wrong with the one supplement shown to do both in numerous studies: creatine mon-hydrate.

For the fastest results, the International Society of Sports Nutrition recommends loading with 0.14 gram per pound of body weight a day (about 25 grams for a 180-pound man) for at least 3 days, and then maintaining with 3 to 5 grams a day.

If you're not in a hurry, taking 2 to 3 grams a day for a month will achieve the same result. Skip the nitric oxide supplements, though. "They're a waste of money," Phillips says. "I'm stunned that they've stuck around as long as they have."

Fight Off Your Fatigue
Beta-alanine is another supplement with solid science behind it. It's an amino acid your body uses to form a compound called carnosine. "Carnosine is found in skeletal muscle, and helps you delay fatigue," Hoffman says.

Early research suggests it could help improve strength and endurance. There's no firm dosage recommendation yet, but University of Oklahoma researchers suggest taking 6.4 grams a day, spread over four doses.

To see results, however, you need to be patient. It takes 2 to 4 weeks to build up enough carnosine in your muscles to have an effect. The good news: Levels stay elevated for weeks after you stop supplementing.

Mix and Match
Combining creatine with beta-alanine can also be a smart move. One of Hoffman's College of New Jersey studies found that college football players who took both supplements (10.5 grams a day of creatine, 3.2 grams a day of beta-alanine) had more productive workouts and less fatigue, and built more muscle than those who took only creatine.

Eat for More Energy
If you're following a daily training regimen, don't eat like a guy who's trying to drop pounds. A study in the Journal of Applied Physiology showed that athletes who trained to exhaustion after 2 days of low-carb eating slowed down the process of building muscle.

"The lower you drive carbohydrates down, the more you need other fuel for energy," Phillips says. "Drop carbs below 40 percent of total calories at that activity level, and you're going to sacrifice performance."

Stay Hungry
To grow a pound of muscle, your body needs about 2,800 calories. If you want to build it in a week, that means you'll need about 400 extra calories a day, says Lonnie Lowery, R.D., Ph.D.

"In our studies, the only times we've seen big gains in muscle are with the men who were the biggest eaters," Phillips says.

Now, if you find yourself struggling to swallow those additional calories (some guys do), the problem could be your go-to protein. While whey is terrific in a postworkout drink, it's also the most satiating type of protein, blunting appetite more than tuna, eggs, or turkey, according to a recent study published in the British Journal of Nutrition.

Burn Fat
Some men don't work out to lose body fat. They eat and train with the goal of becoming stronger or faster or better at their sport, and a great physique is just part of the deal.

In fact, athletes can screw up their chance for glory by focusing too much on appearance—that is, cutting the calories they need to fuel their workouts. But for most of us, better performance is just a nice perk. What we really want is to drop fat without losing muscle.

Calculate Your Carbs
The key to shedding flab is to adjust your carb intake to your activity level. Men's Health weight-loss advisor Alan Aragon, M.S., has a simple way to calculate how many carbs you need.

Multiply your target body weight by 1 if you have a desk job, work out in a gym several times a week for an hour or less, and your main goal is fat loss. Multiply by 2 if you're a recreational athlete who trains for more than an hour a day. And multiply by 3 if you're a competitive athlete who trains multiple hours a day, or if you're a guy with a Mini Cooper body and a Corvette metabolism who is struggling to gain weight.

The number you end up with indicates how many grams of carbs you should eat every day. If you're in category 1 and weigh 180 pounds, that's the equivalent of about two Chipotle burritos.

Eat to Lose Weight
Don't forget the protein. About 25 percent of the protein calories in your food are burned off in digestion, absorption, and chemical changes in your body, so protein has less of a caloric impact.

And perhaps best of all, it defends your hard-earned muscle tissue when you're trying to lose fat.

A recent study in Medicine & Science in Sports & Exercise found that a weight-loss diet with 35 percent of its calories from protein preserved muscle mass in athletes, while a diet with just 15 percent protein led to an average loss of 3 1/2 pounds of muscle in just 2 weeks.

Aim for a daily intake of about 1 gram of protein per pound of target body weight when you're working to lose fat.

Blend the Best Shake
You can boost the appetite-suppressing effect of a whey shake by whipping it to a froth. When Penn State researchers had men drink blended shakes of various volumes, they found that the men who drank the more-aerated shakes ate 12 percent less food at their next meal.

The scientists speculate that the larger appearance of the shakes made men think they were drinking more.

Fight Fat with Fat
A lean body is a well-oiled machine. A 2007 study in the American Journal of Clinical Nutrition showed that people who swallowed 1.9 grams of omega-3s daily and did cardio a little more than 2 hours a week reduced their body fat, lowered their triglycerides, and raised their HDL cholesterol.

Here's the kicker: When another group with the same exercise regimen was given sunflower oil (which has mostly omega-6 fats) instead, they lost hardly any fat. Omega-3s are powerful body sculptors in their own right.

Fixing the omega imbalance is a two-step process. First, says Aragon, take three to six fish-oil capsules a day, for a total of 1 to 2 grams of DHA and EPA. Second, cut back on omega- 6s.

Many salad dressings and mayonnaises are packed with soybean oil, the source of more omega-6 fats than any other food. Choose salad dressings made with extra-virgin olive oil (rich in heart-healthy monounsaturated fats), and use mustard instead of mayo.

Scramble to Slim Down
Not only are eggs a great muscle-building food, but they can also help you look less egg-shaped. A 2010 study in Nutrition Research showed that men who had eggs for breakfast ate less over the next 24 hours than those who began their day with a bagel instead.