1. Your toast lacks B vitamins.
Most bread lacks adequate levels of the B vitamins you need (thiamin, riboflavin, niacin and folic acid) to build serotonin, the neurotransmitter that keeps you calm and happy.
Bitch-proof your breakfast:
Your breakfast should deliver 10 percent of the daily value of thiamin, riboflavin, niacin and folic acid, says dietitian Lisa Dorfman, R.D., a food and mood expert. The amounts of these B vitamins vary by brand, so look carefully at labels. Some breads containing nuts are higher in Bs, as are some that list "whole grain" in the ingredients. If your bread doesn't supply enough Bs, chase your toast with fortified orange juice or switch to fortified cereal - many provide at least 25 percent of these B vitamins.
2. You rely on "low-fat" foods.
Typical low-fat muffins and pastries contain corn and safflower oils. They also often contain unhealthy trans fats. The problem? The wrong type of fat can leave you sluggish and grumpy.
Bitch-proof your breakfast: Some research suggests that people with low levels of the right type of fat - omega-3 fatty acids - are more short-tempered, says Wendy Kohatsu, M.D., assistant professor at Oregon Health Sciences University. Omega-3 fatty acids help form the membranes of your nerve cells, allowing them to function better. Find good fats in walnuts or flaxseed, which you can stir into your cereal or yogurt.
3. You eat fruit by itself.
Fruit has valuable fiber and numerous nutrients, but it leaves you short on magnesium, a nutrient that can ease the symptoms of depression - which include having a super-short fuse.
Bitch-proof your breakfast: Add almonds, soy milk or cereals such as Whole Grain Total, which are all rich in magnesium.
4. You love pancakes and pastries.
"When you're eating only refined carbohydrates such as these, your blood-sugar levels can drop below normal 90 minutes later, making you feel irritable and edgy," says Dr. Kohatsu.
Bitch-proof your breakfast: Add protein, which makes you feel less sluggish and gives your brain the energy to handle daily stress. Think peanut butter, almond butter, eggs, yogurt or cereal with added protein. Sustain that energy by having at least 5 grams of fiber each morning, too. On average, a serving of peanut butter delivers 2 grams of fiber, so you'll want to supplement with an apple or a banana (about 3 grams each).
5. You skip your coffee.
Drinking less than your usual daily dose of caffeine can leave you cranky.
Bitch-proof your breakfast: If you're trying to trim your intake, drink only 10 percent less caffeine a day. Note: This doesn't mean more coffee is better! Drinking more than your usual amount can make you jumpy and nasty, too.