The news is grim: With each passing year, your natural calorie burn slows further. It's a big reason many people find that as they age, they gain weight even though they're eating the same. (Just make sure you don't have one of the nine medical causes of slow metabolism). Artificial sweeteners are a problem because they can change gut bacteria, causing blood sugar to spike and thereby raise your risk for type 2 diabetes and obesity, according to research published in the respected journal, Nature. Instead, opt for water. Not drinking enough water is a major metabolism mistake. "When you feel thirsty, you're likely already one to two percent dehydrated," says Amy Gorin, MS, RDN. "Water may help you feel fuller and help you eat less at meals. It might even help temporarily boost pre-meal metabolism." Gorin goes on to site one study in which obese British adults were asked to drink about two cups of water before eating each of their daily meals. They lost more than nine pounds in about three months, which is a lot more than the people who didn't drink water before meals.
Low-calorie frozen meals
"Some of my clients think it's a good idea to eat frozen meals with just 150 to 200 calories, but instead of helping you lose weight, this type of meal when eaten regularly may actually slow metabolism because you need to eat enough calories throughout the day to help keep your metabolism revving," says Gorin. Frozen foods also tend to be loaded in sodium and lacking in fiber. If you're going to eat a frozen meal, Gorin suggests pairing it with some pulses (beans, lentils, chickpeas, or dried peas). "They offer satiating fiber and protein—and eating just ¾ cup of them daily could amp up your weight loss (in one study, close to a pound in a six-week period). Also add some veggies to your meal—they're full of water, which is hydrating and filling!" See here for more way to get a metabolism of a 25-year-old.
Low protein diets
"Your body expends a good amount of energy to break down and store protein, so make sure you're getting some protein (about 20 to 30 grams) at each meal and spreading this throughout the day," says Gorin who recommends starting your day with a high-protein smoothie with vanilla bean, which boasts 21 grams of protein.
Being healthy doesn't mean eating tasteless food. Spices are one of the best ways to add flavor to healthy, fresh produce without packing on calories (see this for more way to jump start your metabolism). Remember, your diet shouldn't be a temporary change, it should be a long-term pattern of healthy eating, says Gorin: That's not something you can achieve if you don't actually like what you're eating. Adding some spice to your food also gives your metabolism a kick. "In one study, people eating about ½ teaspoon of red pepper (versus people not having any) had bigger post-meal calorie burn," says Gorin.
You probably already know that alcohol is nothing but empty calories, but you might not realize that drinking booze also irritates your gastrointestinal tract, which in the long term can damage your body's ability to absorb nutrients, vitamins, and minerals from the foods you eat. Instead opt for a green tea nightcap, which seems to help metabolism thanks to a substance called EGCG (a type of catechin) and the small amount of caffeine it contains. "Studies show that the caffeine in tea may provide a small metabolism benefit for up to 24 hours," explains Gorin. If you're looking for more of a buzz try kombucha, which is fermented tea and sugar. It has naturally occurring alcohol along with a host of probiotics (aka healthy, metabolism-boosting bacteria).
Some people are sensitive to wheat—and it's in a surprising number of foods. "If the body is sensitive to a food that is being consumed on a regular basis, it will build up antibodies to those foods, fighting them as if they are a foreign invader in the body," explains Christa Orecchio, Integrative Nutrition Health Coach and founder of The Whole Journey. "This puts an extreme inflammatory burden on the gut, liver, and immune system and subsequently, the thyroid, which is the metabolic regulator of the body."
You already know that sugar is bad (some experts want it regulated like drug), but you might not realize that it's also highly inflammatory, and the body doesn't process it well. "The World Health Organization and American Heart Association recommends 25-36 grams of sugar per day; currently, most of us are consuming at least 48 teaspoons," says Courtney Daylong, Integrative Nutrition Health Coach and founder of Totally Fit Mama. So how do we fix this? "To satisfy that sugar craving, reach for real fruit." Yes, it still contains sugar, she says, but it's not concentrated like it is in processed foods. "You will be getting the fiber (which is a big metabolism helper to detoxify the body and get things 'moving'), along with being antioxidants, vitamins, and minerals, all things processed sugar lacks."
Not all carbs are created equal. Refined carbs—think white bread and white rice—have had their whole grains extracted during processing. Refining also removes fiber and pretty much all nutritional value. It's important to minimize refined carbs and instead opt for complex carbs like whole grains, vegetables, fruits, and beans. "These complex carbs will help keep you full and will help keep your blood sugar stabilized longer," says Daylong. Note that if you're looking to trim down, opt for non-starchy vegetables for the bulk of your carbs (think eggplant, broccoli, asparagus, and hearts of palm). Here are the signs you're eating too many carbs.
Daylong believes our diets contain too many omega-6 fatty acids—think vegetable oils, chicken, cereal grains—and without the balance of healthy omega-3 fats, the result can lead to inflammation, which interferes with your metabolism. "Omega-6s are necessary to balance omega-3s, but most of us are out of balance due to all the processed foods we eat," she says. She recommends eating fatty fish like salmon or sardines a few times each week. "Walnuts and flaxseeds are also higher in omega-3s. Quality sourced omega-3 supplements can also be of benefit. All of this will work to naturally fight inflammation."
Some people don't process high levels of dairy protein (casein) or sugar (lactose) very well, which is why they find that dairy can lead to inflammation and bloating. If you're worried that dairy is interfering with your calorie burn, try experimenting with calcium-fortified nut milks like unsweetened almond milk. Just remember that you don't want to miss out on the calcium: Some research suggests that calcium deficiency can also slow metabolism. You could also check out the many surprising calcium sources that aren't dairy-based.