Though the adage coined by American nutritionist Adelle Davis about how one should: “Eat breakfast like a king, lunch like a prince and dinner like a pauper” comes with caveats these days, Davis’ primary point is still heeded by nutrition experts.  That point is, namely, breakfast is important and there will be some side effects if you’re skipping it regularly.

When you start your day with a balanced breakfast—one that has plenty of protein, healthy carbs, and the right mix of vitamins and minerals—your body tends to work at its best. Essentially, you set yourself up for ideal physical health, mental acuity, and stable energy levels.

On the other hand, when you skip breakfast, you may be inviting in a host of problems in both the short term and long term. Here are some side effects you may not know about skipping breakfast.

You will slow down your metabolism

You know how you can delay eating for hours on some days without feeling all that hungry, but if you have even a little morsel of food, you suddenly feel famished for more? That’s because eating revs up your metabolism for the day, according to a study in The Journal of Nutrition. They concluded that eating breakfast as the largest meal of the day prevented weight gain.

And starting it up early is a good thing, as your body is most efficient at secreting insulin, digesting food, and other processes early on in the day after a good night of rest. Delaying eating means delaying starting up these healthy processes and therein reducing their efficacy at subsequent meals.

You’ll feel hungrier later

A healthy breakfast can not only give you the energy and nutrients your body needs to launch itself into the day, but it can also stabilize blood sugar levels to stave off feelings of hunger and associated irritability throughout the day, says Mary Stewart, RD, LD, founder of Cultivate Nutrition, in a recent Yahoo article. By not eating breakfast you could be setting yourself up for failure later in the day, making it harder for you to make healthier choices due to blood sugar fluctuations.

It may cause weight gain

Studies overwhelmingly find that eating a majority of one’s daily calories in the morning is the best way to shed pounds or maintain a stable weight, reports Life Hack. On the other hand, eating larger meals closer to bedtime is correlated with gain weight.

And the same can be said for eating a number of smaller meals and snacks later in the day, too: it’s far better to do the bulk of your eating early. A study at San Raffaele Rome Open University concluded that timing was. even more important than what was being eaten. The study of 18 women showed that those who consumed most of the day’s calories in the first half of the day lost more weight and had improved insulin sensitivity.

Your immune system is weakened

The stronger and more energized your body, the stronger and more energized your immune system. A healthy breakfast can foster a robust, healthy immune response when you come into contact with any manner of bacteria or virus. As we previously reported, “Periods of fasting appear to trigger damage to the cells and the body needs to be fed food regularly in order to maintain healthy levels of immune cells that fight infections and improve the action of fighter cells (T-cells) in the body,” explained Tehzeeb Lalani, a nutritionist with Scale Beyond Scale.

It may cause hair loss

You can file this one in both the “decidedly unexpected” and “definitely unwelcome” columns, but habitually skipping breakfast can lead to hair loss, says The Health Site. That’s because an insufficient infusion of protein in the morning curbs your body’s ability to produce keratin, the building block of your hair (and nails). Without a protein-rich breakfast in the morning, you may well, be leaving more hairs on the pillow at night, and growing less to replace them.

Your stress levels will spike

A study of women 18-45 years old showed increased cortisol levels among breakfast skippers. Cortisol is often called the “stress hormone,” says the Mayo Clinic. And while cortisol can be a vital natural chemical, increasing glucose content in the bloodstream and enhancing your energy levels, sense of awareness, and even your body’s ability to repair damaged cells, an excess in everyday life can leave you feeling fatigued, irritable, confused, depressed, and, quite simply, stressed.

“By having breakfast, you refill the liver glycogen levels so that the cortisol levels can decrease. If you don’t eat breakfast, then cortisol levels will continue to increase to maintain blood glucose levels eventually causing insulin resistance that makes you more hungry throughout the day,” said Dr. Barry Sears, president of the non-profit Inflammation Research Foundation, in a previous article.

You may cause intense headaches

Do you often suffer intense headaches in the afternoons? It could be the fact that you’re not eating a proper breakfast. According to Tata Health, when you forgo breakfast in the morning, you invite in hypoglycemia later, and this is a biological process wherein blood sugar levels drop and blood pressure increases. And, this sudden elevation in blood pressure can cause debilitating headaches.

You may bring on nighttime indigestion

According to Life Hack, it takes a good three hours for a human body to digest foods, so if you compensate for a skipped breakfast at the start of the day with a larger-than-usual dinner at the end of the day, you will almost surely go to bed with undigested or semi-digested food in your system. And that can lead to discomfort and bloating, interrupted sleep, acid reflux, and perhaps even some odd dreams, reports News.

You increase your risk for developing Type 2 diabetes

There are all sorts of acute problems caused by skipping breakfast, such as headaches and sugar cravings but the insidious side effects of missed morning meals can have much larger, longer-term effects on your health as well. In fact for some people, habitually skipping breakfast can dramatically increase the likelihood of the development of Type 2 diabetes. Chronically increased insulin resistance and hormone imbalances caused by improper breakfast practices are the culprits.