Work in Resistance Training
Starting in your late twenties, metabolism slows by 150 calories each decade according to 2005 study from Tufts University. This is mainly due to a gradual loss of muscle; a little loss is a natural part of aging, but some is preventable by staying active and working to maintain muscle mass. Adding 1kg (about 2.2 pounds) of muscle to the body increases RMR by approximately 20 calories per day, and a 2012 study published by the American College of Sports Medicine suggests regular resistance training can increase RMR by 7%. Other perks included loss of body fat and increased bone mass.
Our Advice: Aim to incorporate two to three days of resistance training using body weight, machines, or weights. Make sure to each of the major muscle groups (chest, back, shoulders, biceps, triceps, abdomen, hamstrings, and quadriceps) two times each week.
Cut Workout Time
Research suggests short bursts of high-intensity exercises increase metabolism both during and in the hours following a workout, as well as improve fat breakdown, cardio fitness, and muscle endurance better than longer, moderate-intensity workouts. Referred to as HIIT (high-intensity interval training), these workouts center around all-out exercise for five seconds to eight minutes, followed by a short recovery period before repeating the cycle again, The total workout time ranges from 10 to 30 minutes.
Our Advice: HIIT is the principle behind many trendy and boot camp–type workouts but you don’t have to join a group; the American Council on Exercise (acefitness.org) offers free HIIT workouts for all levels and locations (home, gym, and pool). Research suggests three HIIT workouts a week combined with two to three other days of more moderate activities.
Head to Bed
Not getting enough sleep (or enough quality sleep) triggers hormonal changes that affect metabolism and appetite for up to 24 hours. These include a decrease in RMR as well as increases in appetite and insulin resistance.
Our Advice: According to the National Sleep Foundation, adults should aim for seven to nine hours of sleep nightly for adequate rest. This is often easier said than done, so look for ways to go to bed earlier, remove distractions (like a TV and phone) from the bedroom, and let yourself catch up on sleep when needed. Getting adequate sleep isn’t being lazy; rather, it’s downtime so your body can perform at max capacity each day.
Research from Ohio State University suggests women who reported one or more stressful events in the past 24 hours burned 104 fewer calories after consuming a standard fast-food breakfast meal compared to women who had no stressful events. This decrease in metabolism is attributed to higher insulin levels caused by stress that slow fat breakdown and promote body fat storage.
Our Advice: To keep your metabolism burning efficiently, focus on reducing short-term stressors that pop up during the week using exercise, meditation, listening to music, or other activities to help you relax.
If you don’t eat enough, metabolism decreases initially as body functions slow to conserve energy. If lack of food continues, muscle is also broken down for energy—meaning metabolism takes a short- and long-term hit.
Our Advice: Women should stay above 1,200 calories daily and men 1,500 calories to avoid this effect.