Your boyfriend's man habits — like housing 12 sliders in one sitting — might seem somewhat endearing (and remarkable/annoying if he never gains a pound). But the truth is that some of those boyish behaviors are actually quite destructive. Look out for these signs and encourage him to hit up his doctor if you have any cause for concern.

1. He drinks more beer than water. Yes, guys can metabolize alcohol more effectively than women. But that doesn't mean he can make beer his primary source of hydration. Over time, heavy drinking can bring on stomach ulcers, liver problems, depression, and issues with his reproductive system.

2. He's too cool for sunscreen. Guys may be more stubborn about lathering up, but they're just as prone to sunburn and skin cancer as women: Research suggests that every single sunburn increases the risk of skin cancer, which could crop up in the form of new or changing lumps, bumps, spots, sores, or other skin marks (particularly in places he can't easily see, like his back.)

3. He never goes to the doctor. Biannual dentist visits can help detect gum disease and cavities before things get messy, and annual checkups can unearth any lurking health issues so they don't become bigger issues.

4. He's always eating out. If he's not cooking for himself, he's more likely to overdo it on calories, fat, and sodium, according to a Public Health Nutrition study. And if he stocks his pantries with processed snacks and frozen pizzas, he's no better off: Packaged foods tend to fall short on nutrients and contain preservatives and other unnecessary ingredients added to make food look more appealing.

5. He loves red meat too much. Processed red meats (like sausage and salami) increase risk of heart failure and death related to heart disease among men in particular, according to a Circulation: Heart Failure study. While it's safe to eat red meat a few times a week, it's all about the balance: He should be getting protein from other healthy sources such as chicken, low-fat yogurts, and cheese. And pairing Big Macs with something that grows from the ground — extra credit if it's green.

6. His pants don't fit. It's tough to assess a guy's diet without tracking his every bite, but tight-fitting clothes (or particularly loose ones) can tip you off to unhealthy habits, like eating too much crap or moving too little.

7. He drinks when he's stressed. Contrary to what you might think, drinking alcohol is a sign of failure in the stress-management department. This unsustainable coping mechanism is so much worse than healthier habits like exercise and talk therapy.

8. He pees a million times a night. Midnight bathroom runs don't just disrupt your beauty sleep — they could be a symptom of kidney, bladder, or penis infection; renal stones; a tumor; diabetes; or prostate disease, says David Gremillion, M.D., a men's health expert and professor at University of North Carolina School of Medicine. If he wakes up to pee more than once or twice per night, it could be cause for concern.

9. He thinks butter is a core food group. Because youngish guys are especially susceptible to blood vessel damage caused by unhealthy dietary fats, a diet full of food prepared with butter could set your boyfriend up for heart disease and stroke, Dr. Gremillion says. While the dangers of saturated fat have recently been called into question, it can't hurt to swap butter for other seasonings — or encourage him to douse his bread in a monounsaturated fat that's proven to be healthful: extra virgin olive oil.

10. He guzzles sweetened fruit juice. Like soda, fruit juice contains tons of added sugar and calories that your body doesn't recognize as solid food. Don't let the fruit part fool you: The vitamins and minerals found in juice don't offset the negative effects of drinking hundreds of empty calories (regardless of whether he's counting them). As if there was any doubt as to whether these calories can lead to weight gain, now, experts are saying that the sugar found in fruit juice could trigger cravings for high-calorie foods.

11. He barely ever exercises. Regular exercise is an essential part of maintaining a healthy body. So no, a random pickup basketball game here and there won't do any favors for long-term fitness, disease risk, or chronic stress — and it could even set him up for injury when he does make moves.

12. He's got a big-time belly. Most guys are naturally bigger-boned than women, but the problem is when he carries his extra weight in the gut. Belly fat is linked to greater risk of heart disease, colorectal cancer, sleep apnea (or lack of breathing while you sleep), and type-2 diabetes — which are way scarier than seeing that beer belly at the beach.

13. He's supremely lazy. If your partner splits his time between his office chair and couch, and he moves very little in between, his sedentary lifestyle could be setting him up for chronic disease, according to review of 47 related studies recently published in the Annals of Internal Medicine.

14. His penis looks a little … off. It's entirely possible that you're more familiar with his man parts than he is, Dr. Gremillion says. So look out for lumps or swelling at the base of the penis, which could tip you off to an infection or tumor. If you see any kind of ulcer, particularly one with discharge or swelling, he could have a potentially infectious sexually transmitted disease. If anything remotely grosses you out, it's could be bad news and definitely needs to be checked out.

15. He gets totally winded after walking one flight of steps. Climbing stairs is a good indicator of physical fitness, Dr. Gremillion explains. If a single flight leaves him breathless, he's probably not in great shape.

16. He sweat-soaks the sheets every time you have sex. It's normal for things to heat up during sex, which increases the heart rate kind of like regular exercise. But excessive perspiration could mean something is wrong with his response to physical activity, Dr. Gremillion says.

19. It takes him forever to recover from an orgasm. If it takes longer than five minutes for his heart beat to return to normal, Dr. Gremillion says it could be suffering from angina pectoris, or reduced blood flow to the heart. While Olds have a higher risk of this condition, it can affect younger guys who are way out of shape, smoke cigarettes, or deal with lots of stress.

21. Your pet name for him is "Mr. Negative." Unrelenting cynicism and negativity doesn't just bring you down — it could be a sign of depression. (Because many guys struggle to admit they have feelings, convincing them to get help can be a hard sell. But you're probably the best person to make the case for talk therapy if you think he could have a mood disorder.)

22. His snoring could wake the dead. It's not just a nuisance — snoring and sleep apnea often go hand in hand. They're associated with higher rates of stroke, heart attack, hypertension, and sudden death — a risk that will only increase as he ages.

23. He's always tired. Excessive sleepiness could be a subtle symptom of anxiety or bad eating habits, or other conditions that can't be solved by an extra cup of coffee. Regardless of the reason, science suggests that sleep deprivation throws the immune system out of whack, so skimping on sleep will only compromise his health more.

24. He smokes cigarettes. This one doesn't need an explanation: It's a one-way express ticket to terrible health.