Do you ever wonder why it’s so hard to give up junk food when you are trying to eat healthy? Why do you find yourself reaching for the chips when you know you should be grabbing carrots instead?

Scientists are trying to figure out why the obesity rates in America have jumped dramatically over the past 20 years. According to the Trust For America’s Health report called “F as in Fat: How Obesity Threatens America’s Future 2011“, no state had an obesity rate above 15 percent 20 years ago. Today, 38 states have obesity rates over 25 percent. Since 1995, obesity rates have doubled in seven states. Obesity rates have grown fastest in Oklahoma, Alabama, and Tennessee, and slowest in Washington, D.C., Colorado, and Connecticut.

During this same time, consumer access to information about fitness and nutrition has exploded. The internet age has ushered in media tools line online blogs, videos, and tools for people to learn about the impact of their health habits on their weight.

So why is it so hard to follow the advice of doctors, trainers, and nutritionists if all of the information is out there for anyone to access? While you may feel shame about making the wrong choices, you shouldn’t beat yourself up over it. It’s not a matter of sheer willpower. You may be addicted to junk food, according to recent studies.

Here’s why:

Food Engineering

Food manufacturers hire world-class chemists to engineer the food that you purchase in the grocery store. Have you ever wondered why “natural and artificial flavors” are listed on the wrapper of your favorite snack? The food manufacturer hired a food chemist to develop a flavor profile to add to the main ingredients.

These flavor profiles are designed with palatability in mind. Palatability is the reward signal that your brain gets from eating a food that is pleasing in taste, texture, and complexity. The foods that are most palatable combine fat, salt, sweetness, layered texture, and aroma to induce a pleasing reaction in the brain.

Think about pizza for example. Pizza is a popular junk food because it is highly palatable. It’s salty, sweet (the crust is converted to sugar in the body), fatty (thanks to the cheese), and contains many layered textures (crunchy, gooey, cheesy). Who can resist the aroma of a pizza fresh out of the oven?

Scientists use these same factors to design junk foods. A food example of this would be oreos, which were my favorite as a kid. I could basically clear a whole tray of oreos if my mother wasn’t monitoring me. The oreo is the perfect food in terms of palatability. It has a robust chocolate and vanilla flavor that is sweet with a hint of bitterness and salt (in the chocolate cookie), it has layered textures (creamy and crunchy), and smells sweet.

Foods with high palatability are harder to stop eating. That’s why I could never eat just a few oreos as a kid.

The Reward Factor

The reward factor is a set of biological processes that happen in the brain after you eat a highly palatable food. In obese people, these biological processes are weaker due to longterm overstimulation from highly palatable food.

For example, when a non-obese person is hungry and satisfied, the signals are stronger. This means that they have strong hunger cravings sometimes during the day, punctuated by long periods of satisfaction after eating. Scientists have found that obese people have lower levels of hunger that are constant throughout the day, and they are never fully satisfied no matter what they eat. This causes them to eat more, and more frequently.

Food Marketing

You’ll never see apples, cucumbers, grass-fed beef, or omega-3 rich fish as the stars of a food marketing campaign. Why? Because they aren’t backed by mega-corporations that are selling you a manufactured product.

Food marketers don’t care about your health or your weight. Their job is to get you buy what they are selling – and lots of it! Food marketing is just the final psychological trick to get you hooked on junk food. As if it’s not bad enough that junk food is designed to be addictive and causes diminishing hunger returns, it’s also sold to you in a way that makes you think that your life will be better with it.

Sounds like alcohol or cigarettes, right?

Just like it can be difficult to shake addictions to substances like alcohol and cigarettes, it can be just as difficult to reset after a lifetime of being addicted to junk food. If you think that you may be a junk food addict, here are some strategies that nutrition experts employ to get their clients to kick junk food:

1) “Balance blood sugar. Blood sugar highs and lows drive primitive food cravings. If you get famished between meals, that’s a sign that your blood sugar is crashing. When blood sugar is low, you’ll eat anything. To better balance blood sugar, eat a small meal or snack that includes healthy protein, like seeds or nuts, every 3 to 4 hours.” – Dr. Mark Hyman

2) “Stop buying any products you find difficult to resist. Shop at smaller grocery stores that emphasize fresh food. Whole Foods at least does not sell products with transfats in them (one of the most addictive substances).” – Ariane Benefit, M.S.Ed.

3) “Develop a healthy support system with likeminded friends, and seek professional counseling for the deep stuff. Isolation fuels pent up emotions like kerosene fuels a fire. I learned to process and communicate my thoughts and feelings on the member center instead of turning to food. The gift of understanding that others gave was priceless, and helped me establish a new path of emotional health.” – Emily Boller

4) “To kick your addiction, you have to detox your liver. Replace grains with broccoli or cauliflower for one week, and eat garlic, chives and leeks. For withdrawal, take a Vitamin B complex and 1,000 mg a day of chromium picolinate. Eat meat in a 4:1 ratio, limiting it to a quarter of your protein. Also eat leafy greens and citrus.” – Dr. Mehmet Oz