Metabolism is the process by which the body creates energy from the food we eat. The sugars found in food are broken down into usable glucose, which is the “food” of the body’s cells. Glucose is converted into a substance called ATP (adenosine triphosphate), which the cell uses as energy. While weight gain isn’t caused by slow metabolism alone, metabolism does play a large role in a concept known as “age-related onset of obesity”. 
Your body’s metabolism is a very fickle thing. There are a variety of external factors that contribute to it speeding up or slowing down – but metabolism is certainly affected by age: It is a known fact that with increasing age comes slowing metabolism. High-calorie food items like fast-food fries and chips, that appear to be eaten by some teenagers without noticeable weight gain, can cause much greater weight gain to people in their late twenties or older – simply because of significantly slower metabolism.
Age-related onset of obesity has been the focus of many studies on metabolism in recent years. In 2015, a study was published by Wee, Y., et. al. on the effects of age on the body’s metabolism, specifically how age causes metabolic dysregulation. The results revealed that neurological decline over time could disturb the body’s normal metabolic process, leading to obesity. Inflammation in brain tissue and alteration of genes (seen in aging) are cited as the specific events involved in neurological dysfunction. 
Here are 10 ways you can boost your metabolism and stave off weight gain:
- Coffee, Tea to Lose LBS
Green tea is not only loaded with antioxidants that help get rid of circulating free radicals which damage the body’s tissues, it also boosts the body’s metabolism that help with natural weight loss. An old study published in 1999 found that green tea was able to boost the body’s metabolic rate by 4 percent through fat oxidation and thermogenesis. This study became the basis of many studies on green tea and metabolism: For example, Cardoso, et. al. in 2013 found that green tea intake accompanied by exercise caused an increase in resting metabolic rate, lean body mass, and muscle strength, plus a significant decrease in body fat, waist circumference, and serum cholesterol. 
On the other hand, caffeine has also been found to increase metabolic rate and cause weight loss in a 2015 study by Liu, et. al.. The study focused on caffeine intake (with albuterol) with the results revealing a significant increase in lean body mass and decrease in fat mass after four to eight weeks – all without changes in food intake. 
- Get Regular Aerobic Exercise
The American Heart Association recommends at least 150 minutes of moderate exercise per week (cut that time in half for vigorous exercise) to promote cardiovascular health. A recent study by Gim and Choi (published in 2016) found that regular exercise increased resting metabolic rate in adults, with increases in individual exercise leading to parallel increases in metabolic rate – and eventual loss (or maintenance) of weight. 
- Eat Enough Food
Yes, you did read that correctly. When people hear the words “weight loss”, it often brings up images of crash dieting – a short-term effective but very unhealthy way (and deadly for some) to lose weight. Crash dieting involves starvation of the body’s cells because your body’s metabolic rate remains the same as you deprive it of needed glucose (and therefore energy) to function. Therefore, your body literally starts “eating” itself – metabolizing fat and eventually protein stores in muscles.
However – this eventually slows your metabolic rate, which would actually make it harder to lose weight in the end. Instead of depriving your body of food, which often leads to binge eating, make sure to stick to your normal daily caloric intake (which is based on your age, weight, and physical activity) and get enough fruits and vegetables in your diet. 
- Protein, Protein, Protein
Instead of adding carbohydrates and fat through your diet, opt for more protein instead! Protein from eggs, lean meat, and milk can boost your resting metabolic rate according to a study by Matinolli, et. al. published in 2015. Although the study’s test subjects focused on neonates, the results concluded that additional protein intake was able to promote health body composition and higher metabolic rates in adulthood. 
- Use More Spices
This is interesting: Did you know that spiced food has effects on your body’s metabolism? It all has to do with a process called thermogenesis, literally meaning “creation of heat”. This process plays a big role in metabolism, since heat is a form of energy. A study in 2006 on spices and metabolism found that capsaicin, black pepper, ginger, and mixed spices (among others) caused increases in the body’s metabolic rate that may help battle obesity. 
- Lift Weights
The second item on this list is directly linked with this one – more lean muscles equal better metabolism and increases in weight loss. A study published by Steinberg, et. al. in the American Journal of Physiology found that muscles in obese people promoted higher uptake (storage) of fatty acids compared to lean muscles. Lean muscles, on the other hand, had better rates of metabolism and oxidation – leading to more efficient weight loss. 
- Get Enough Sleep
When you sleep, the body “resets” itself. It is a period where the body regulates its normal processes – and that includes metabolism. A 2010 study found that sleep deprivation causes metabolic dysregulation by affecting glucose metabolism and hormones responsible for it (specifically leptin and ghrelin). So in order to improve your energy throughout the day and your metabolism, be sure to get enough sleep. 
- Drink Water After Waking Up
Water has many health benefits – better hydration and digestion, as well as maintaining body homeostasis. While there is no hard evidence to support that concept that water intake immediately after waking up affects metabolism, many people swear by it. This is rooted in the idea that drinking water after you wake up somehow “boosts” your body’s metabolism and also affects your appetite early in the morning by filling the stomach (meaning you eat less = weight loss). There are no negative effects to water intake upon waking up so it wouldn’t hurt. You’re better hydrated either way.
- Snack Smart
People affected by diabetes have problems with insulin and glucose metabolism – which is why they are advised SFF – or small, frequent feedings. This helps keep your metabolism going – if you snack smart! Don’t snack on junk food, opt for fresh fruits and vegetables instead. In 2015, a study by Alencar, et. al. found that increased meal frequency was able to preserve fat-free mass in terms of body composition, although there were no significant changes in metabolism. 
- Drink Over 100 Ounces Water Per Day
Despite a lack of scientific research on water intake immediately after waking up, there have been several studies on water intake in general and the body’s metabolic rate. Boschmann, et. al. in 2003 found that drinking an additional 500 milliliters of water caused increases in metabolic rate by as much as 30 percent – and that this increase happened within ten to 40 minutes after intake. The study concluded that drinking that much water per day promotes natural weight loss. 
10 Foods To Boost Metabolism
The following food items could will boost your metabolism, so find ways to include several in your daily meals for an added boost.
Grapefruit is great as a juice in the morning or as a fresh fruit snack. A study found that naringenin, a citrus flavonoid found in grapefruit, was able to regulate the body’s metabolism of glucose – helping prevent diabetes and weight gain. 
- Steamed Broccoli
The perfect side dish to any meal, or add it to your green juice in the morning! Research done by the Institute of Food Research found that broccoli is able to regulate or “retune” the body’s metabolism (helping with weight loss) – which wanes as we age. 
Almonds are another healthy snack option; interestingly, they appear to be better than other nut snacks that increase your body’s cholesterol intake. A study found that almonds were able to contribute to better lipid metabolism and reduction in anthropometric measurements in test subjects. 
Oatmeal is a great source of fiber, which promotes healthy digestion, and excretion of waste – this alone can cause improvements in weight loss and nutrient absorption. Because of its low glycemic index of 55, it also helps regulate your body’s ability to metabolize glucose. 
Kale is considered one of the healthiest food items today because it has low caloric content while packing an amazing amount of vitamins and minerals. The low caloric content helps with weight loss and the nutrients help regulate metabolism – especially vitamin C. A study in 2005 has found that vitamin C plays a role in fat mass loss and metabolism. 
Ginger is one of the spices included in the study on spices and metabolism. You can add ginger to your fruit juice for an extra kick or in a stir-fry of vegetables and lean meat. You can even try ginger tea in the morning or afternoon for added metabolism boost before breakfast and dinner.
- Salmon And Tuna
Salmon and tuna are great sources of lean protein to lower your caloric intake (and to help improve your metabolism!) Salmon and tuna are popularly used in salads or even as main dishes for lunch or dinner. A tuna sandwich is a great snack alternative to ham as well.
Garlic is a spice that can help with thermogenesis and metabolism. You can add roasted garlic to pasta or lean meats like seared salmon or beef. A stir-fry with garlic would be a great way to add it to your diet.
- Low-fat Yogurt
Yogurt is an outstanding low calorie, high protein snack alternative. This is an excellent breakfast food – you can even mix in some grains or fruits for more benefits.
- Lean Protein
As previously mentioned, adding protein to your diet can help boost metabolism significantly. Get your daily dose of protein from lean meat like chicken breast and lean cuts of beef.
1] Mayo Clinic. Metabolism and weight loss: How you burn calories. http://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/metabolism/art-20046508
 Wee, Y., et. al. (2015). Age-Related Onset of Obesity Corresponds with Metabolic Dysregulation and Altered Microglia Morphology in Mice Deficient for Ifitm Proteins. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4391874/
 Dulloo, A., et. al. (1999). Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. http://ajcn.nutrition.org/content/70/6/1040.full
 Cardoso, G., et. al. (2013). The effects of green tea consumption and resistance training on body composition and resting metabolic rate in overweight or obese women. http://www.ncbi.nlm.nih.gov/pubmed/23140132
 Liu, A., et. al. (2015). The effect of caffeine and albuterol on body composition and metabolic rate. http://www.ncbi.nlm.nih.gov/pubmed/26239482
 American Heart Association. American Heart Association Recommendations for Physical Activity in Adults. http://www.heart.org/HEARTORG/HealthyLiving/PhysicalActivity/FitnessBasics/American-Heart-Association-Recommendations-for-Physical-Activity-in-Adults_UCM_307976_Article.jsp
 Gim, M. & Choi, J. (2016). The effects of weekly exercise time on VO2max and resting metabolic rate in normal adults. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868243/
 National Health Services. Why is gradual weight loss better than a crash diet? http://www.nhs.uk/chq/Pages/2468.aspx?CategoryID=51
 Matinolli, H., et. al. (2015). Early Protein Intake Is Associated with Body Composition and Resting Energy Expenditure in Young Adults Born with Very Low Birth Weight. http://www.ncbi.nlm.nih.gov/pubmed/26180246
 Westerterp-Plantenga, M., et. al. (2006). Metabolic effects of spices, teas, and caffeine. http://www.sciencedirect.com/science/article/pii/S0031938406000540
 Steinberg, G., et. al. (2002). Leptin increases FA oxidation in lean but not obese human skeletal muscle: evidence of peripheral leptin resistance. http://ajpendo.physiology.org/content/283/1/E187.short
 Sharma, S. & Kavuru, M. (2010). Sleep and Metabolism: An Overview. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2929498/
 Alencar, M., et. al. (2015). Increased meal frequency attenuates fat-free mass losses and some markers of health status with a portion-controlled weight loss diet. http://www.ncbi.nlm.nih.gov/pubmed/25862614
 Boschmann, M., et. al. (2003). Water-induced thermogenesis. http://www.ncbi.nlm.nih.gov/pubmed/14671205
 Bahadoran, Z., Mirmiran, P., & Azizi, F. (2013). Dietary polyphenols as potential nutraceuticals in management of diabetes: a review. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3751738/
 Armah, C., et. al. (2013). A diet rich in high glucoraphanin broccoli interacts with genotype to reduce discordance in plasma metabolite profiles through modulating mitochondrial disfunction. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3743733/
 Abazarfard, Z., Salehi, M., & Keshavarzi, S. (2014). The effect of almonds on anthropometric measurements and lipid profile in overweight and obese females in a weight reduction program: A randomized controlled clinical trial. http://www.ncbi.nlm.nih.gov/pubmed/25097630
 Harvard Health Publications. Glycemic index and glycemic load for 100+ foods. http://www.health.harvard.edu/diseases-and-conditions/glycemic_index_and_glycemic_load_for_100_foods
 Johnston, C. (2005). Strategies for healthy weight loss: from vitamin C to the glycemic response. http://www.ncbi.nlm.nih.gov/pubmed/15930480