Iron deficiencies can slow down your metabolism. Do you know what’s got plenty of it? Lean meat. Eating three to four daily servings of iron-rich foods will help keep your inner furnace burning. Fortified cereals, dried fruit, and dark leafy greens will get you on your way to meeting your iron goals, but lean meat—with its high muscle-building protein content—will be doubly useful in revving up your metabolism.
You’ve heard they're bad for you. But trans fats also slow down your body's ability to burn fat. "They have an altered shape and make your biochemistry run funny," Hyman says, explaining that trans fat binds to fat and liver cells and slows metabolism. Eating trans fat can also lead to insulin resistance and inflammation, both of which cripple metabolism and can cause weight gain.
Muscles are fat-burning furnaces, so be sure to do enough resistance training to build and maintain them (these fast workouts tone your whole body in 30 minutes), and follow your workout with a healthy meal or snack that contains protein, carbohydrates and fat. Building new muscle raises your Resting Metabolic Rate (RMR) so you'll burn more calories every day.
Long-term stress can make you fat, studies have found. "When you're chronically stressed, your body is flooded with stress hormones, which stimulate fat cells deep in the abdomen to increase in size and encourage fat storage," says Peeke. "I call this toxic weight, because fat deep within your belly is more likely to increase your risk for heart disease, diabetes, and cancer." And stress hormones spark your appetite, making you likely to overeat.
Dehydrated cells and organs don’t function as well as they should, leaving your metabolism lower than it could be if you’re not fully hydrated. Water is best, but you can also increase your hydration levels by consuming other beverages too. Just make sure they don’t have high calorie or sugar levels. (This suggestion works especially well for college students who hope to avoid the Freshman 15!)
We all know sitting around too much is really bad for our health: One meta-analysis reported that prolonged sedentary time was associated with harmful health outcomes, and many other studies have shown it can (obviously!) lead to weight gain. Limiting your time in front of the TV at night and even trying to stand more while you're at work — perhaps with a standing desk — can increase your metabolism, helping you lose weight with minimal effort.
The smoothie revolution is here, and lots of people are swilling down bushels of leafy greens. Believe it or not, there’s a downside to this ingenious delivery method. A big part of the body’s job—breaking down food so that the body can absorb nutrients—has been outsourced to our Nutribullets and Vitamixes. That means that the body is expending much less energy than it would if we were eating kale, spinach, and bananas in their solid form. Smoothies are great for weight loss, but by prioritizing lean meats, fish, fibrous vegetables and fruit, you are driving up TEF (the Thermic Effect of Food, or your metabolic rate after eating) and expending more calories on digestion.
Just dropping pounds probably won't help, though, since most weight loss is a combination of fat and muscle tissue. "Usually, when people lose weight, their metabolism actually goes down," says Kim Sasso, a nutritionist at Loyola University Health System. That makes sense; you don’t need as much food to maintain a lower bodyweight. But if your goal is simply to up your metabolism, Sasso says, "it's not until you start decreasing your percentage of body fat and replacing it with increased muscle mass, do you start to see a difference in your resting metabolic rate."
Going organic can be costly and leave a dent on your wallet, but it can speed up your metabolism. The antibiotics and growth hormones found in conventionally farmed foods could hamper your immune system and slow down metabolism. The amount of pesticides in non-organic foods can cause a above normal dip in metabolism in dieters who begin to lose weight, says Prevention.com.