According to Dr. Leo Galland, author of The Fat Resistance Diet, your ability to lose weight depends on a hormone called leptin and how it functions in your body. Under normal circumstances, Dr. Galland says that leptin is a hormone produced by fat cells that turns down your appetite and speeds up your metabolism. This signaling mechanism, he says, helps your body maintain a normal body weight.

If you have trouble losing weight or are chronically overweight, Dr. Galland says there's a good chance your body has become leptin resistant. Dr. Galland says that according to recent studies, the cause of leptin resistance is chronic inflammation. Inflammation not only causes leptin resistance—it also increases a person's risk of developing obesity-related diseases, including heart disease, high blood pressure, diabetes and Alzheimer's disease, he says.

By eating the right foods and eliminating those that cause inflammation, Dr. Galland says you can restore leptin to its normal functioning and lose weight. "The whole purpose of the Fat Resistance Diet—of an anti-inflammatory, nutrient-dense diet—is to allow leptin to work properly," he says.

Dr. Galland shares with Dr. Oz which foods you should avoid and which foods you should consume to combat inflammation and boost your body's fat-fighting abilities:

• Avoid trans fats. "Trans fats are among the worst inflammatory foods that you can eat," Dr. Galland says, because they interfere with the activity in the body of the essential fats, omega-3s and omega-6s.
• Avoid sugar. Dr. Galland says simple sugars have an inflammatory effect because they boost insulin levels.
• Limit saturated fats. Saturated fats are typically solid at room temperature, Dr. Galland says, and are not essential—meaning you can make them in your body.
• Consume the right ratio of essential fats. Some good sources of omega-3s are fish and fish oil, green leafy vegetables, flaxseed and walnuts, as well as soy and some beans. Ideally, the ratio of omega-6s to omega-3s should be somewhere between 3–6 to 1. "It's a little bit like an orchestra; it's not just one or the other," he says.
• Avoid processed foods. Dr. Galland says processed foods contain numerous inflammatory ingredients.