If you have a slow metabolism, your genes may be to blame. Or you may not have enough lean muscle mass. People with lean, muscular bodies burn more calories than people with a higher percentage of body fat.
“There are so many more factors at play, and these include genetics, environment, sleep habits, and muscle mass, among others. Weight management is incredibly complicated,” says Amy Gorin, RDN, who specializes in plant-based eating in Stamford, Connecticut. While clearly difficult, weight loss is not impossible.
You've Gained Muscle Mass
If you're exercising regularly and doing a mix of cardio and strength training, it's very likely your body composition (ratio of muscle to fat) is changing for the better. If you're gaining muscle while losing fat, the scale may not show any weight change.
One of the main reasons that undereating can lead to weight gain is because consuming too few calories can cause your resting metabolic rate to slow down. This means you may burn fewer calories throughout the day.
This phenomenon is called “starvation mode,” and while your body isn't actually starving, it will naturally hold onto whatever calories it receives in an effort to help you maintain your energy balance.
Muscle Mass
A month or two after you start exercising, your body composition may begin to change. You will likely gain muscle mass and may begin to lose some fat mass. Muscle weighs more than fat, but it also burns more calories.
It kicks in to preserve and store fat for future energy. Research shows that this happens because the human body has evolved to value storing fat and energy and to interpret a shortage of calories as sign of distress.
When the calories you burn equal the calories you eat, you reach a plateau. To lose more weight, you need to either increase your physical activity or decrease the calories you eat. Using the same approach that worked at first may maintain your weight loss, but it won't lead to more weight loss.
For most overweight people, their body tries to prevent permanent weight loss. This means your body is actually working against you to lose weight. That's because how much you weigh is controlled by complex interactions between hormones and neurons in your hypothalamus.
As you eat less, your body produces less leptin. This hormone, also known as the satiety hormone, makes you feel full and encourages the burning of fat. If you eat less food, your body produces less of it, which can make losing weight harder. As you lose weight, BMR drops.
But what some people may not realize is there's such a thing as eating too little for weight loss. It's true, says Lisa Young, Ph. D., R.D., a nutritionist and adjunct professor of nutrition at New York University—cutting too many calories can actually slow down the weight loss process.
However, calorie intake should not fall below 1,200 a day in women or 1,500 a day in men, except under the supervision of a health professional. Eating too few calories can endanger your health by depriving you of needed nutrients.
The diet doesn't have enough calories
Eating too little — say, 1,000 calories a day — can prevent you from losing weight, too. "When you don't eat enough, your body is starving and it's not going to lose any extra weight" because it needs those energy stores to keep you alive, Fakhoury said.
Overall, individuals who increased their sleep duration were able to reduce their caloric intake by an average of 270 kcal per day – which would translate to roughly 12 kg, or 26 lbs., of weight loss over three years if the effects were maintained over a long term.
So, if you're eating 1,200 calories and not losing weight, it could be that your body is really struggling to function on so little fuel and your metabolism is not functioning well enough to respond to a deficit in the way you'd like.
As we reach our 30's, our bodies usually need less energy, meaning we may not be able to eat the way we did in our 20's. Then, as you move past 40 and head to middle age, changes in muscle, hormones and metabolism all make it harder to stay trim. But it's not a lost cause.
Although the prevalence of obesity increases with age, weight gain is actually greatest across the younger years of adult life — late twenties and thirties — and diminishes gradually over time as adults get older, says Tucker.
The finding of the study suggests that people in middle age certainly gain weight and it is harder for them to lose it, but slow metabolism is not the real reason behind it. It was revealed that from the 20s to the 50s the energy expenditure is the most stable.
Atleast 30-45 minutes of cardio workout. This can be brisk walking and alternate jogging(start by walking and increasing your speed, slowly jog for about 1 minute and slow down), repeat for 20 minutes followed by continuous walking at a consistent speed. Cardio helps loosen the entire body fat.