Weight management is more urgent than ever due to the burgeoning obesity epidemic and its consequences. As hard as many people strive to lose fat stores, those extra pounds can sneak back uninvited. Researchers are finding that there is more to weight gain than just what we eat or how we exercise. Many factors can stealthily conspire to pack on weight, gradually or suddenly. They do include dietary and activity choices, but underlying health conditions may also factor in.

Low-Calorie Sweeteners

In small amounts, artificial sweeteners such as sucralose and aspartame may assist in weight loss and enhance metabolism. However, George Washington University scientists found that these alternatives could also cause our bodies to create and store fat. Their studies suggest that these sweeteners heighten the activity of glucose transporters, genes that increase glucose entry into fat cells.

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Pharmaceuticals could be responsible for up to 15% of obesity cases, according to the Cleveland Clinic's Bariatric and Metabolic Institute. Some drugs cause the body to burn calories more slowly. Others stimulate the appetite or alter the digestion and storage of nutrients and sugars. They may also encourage water retention. Medicines associated with weight gain include:

  • Steroids
  • Beta-blockers for hypertension
  • Diabetes drugs
  • Antipsychotic medications
  • Antidepressants

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Women in the early stages of menopause often experience weight gain in addition to hot flashes, decreased libido, and irregular periods. This phase, called perimenopause, is marked by fluctuating hormones. Some findings suggest that low estrogen and progesterone levels could heighten the risk of obesity. Another possible factor in perimenopausal weight gain is the erratic production of hormones related to appetite, which spurs increased caloric intake. One study reported that women in perimenopause have higher levels of the hunger hormone ghrelin than pre- and post-menopausal women. Decreased estrogen may also impede the functions of neuropeptide Y and leptin, hormones that regulate satiety.

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Viral Infection

In some cases, a virus is responsible for weight gain. Several microbes promote adipogenesis, the formation of fat cells. A paper in the European Journal of Pediatrics explored the possibility of infectobesity, the hypothesis that infectious agents may cause obesity. Much research focuses on human adenovirus-36, the first virus reported to have adipogenic potential. Adenoviruses affect the respiratory and gastrointestinal tracts, mostly in children. A Finnish study noted that participants who gained excess weight during the 29-year study period were more likely to test positive for AD-36 than those who did not gain weight.

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Uterine fibroids are mostly benign, small, and asymptomatic; the masses grow in the muscle tissue of the uterus, primarily in women in their thirties and forties. In the relatively few cases where fibroids reach a significant size, they make the uterus expand. This exerts pressure on the gastrointestinal and urinary systems, leading to bloating and feelings of heaviness. Uterine fibroids can grow up to 40 pounds, causing swelling that makes a woman appear pregnant. A combination of heavy fibroids, discomfort, and fatigue from anemia may induce significant weight gain. Scientists believe that excess production of sex hormones estrogen and progesterone stimulates fibroid development. Fortunately, this condition is fairly easy to diagnose.

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Obesity has long been regarded as a risk factor for the onset of type 2 diabetes mellitus. However, the results of 2004 study suggest the opposite. Researchers discovered that insulin resistance primarily occurs in the muscle tissues of lean people at risk for diabetes. They concluded that this resistance is the cause of fat accumulation related to type 2 diabetes.

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Dysbiosis, an imbalanced gut microbiome, can incite metabolic processes that promote obesity. People carrying excess weight tend to have lower bacterial diversity and different proportions of gastrointestinal microbes than leaner individuals. Antibiotics change the composition of gut microbiota, and they are associated with obesity, especially among children. Naturally, the diet has an immense impact on the health of gut microbiota, influencing metabolism and inflammation. Researchers are exploring how foods and food supplements can enhance gut health to relieve obesity. One study found that prebiotics can help reduce body weight in children.

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The thyroid, a butterfly-shaped organ at the base of the neck, is a "master gland" that helps regulate metabolism. Dysfunction impacts the production of hormones, the ability to burn calories, and much more. An underactive thyroid — hypothyroidism — could cause issues including emotional upset, goiter, and weight gain. Typically, advanced hypothyroidism correlates to greater weight gain. However, most of the extra pounds are due to salt and water accumulation. This condition alone rarely causes substantial weight gain.

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About one out of five women deal with polycystic ovarian syndrome, a medical condition associated with infrequent menstrual cycles, male pattern baldness, and obesity. Physicians understand that an imbalance of estrogen and testosterone is associated with the disorder, and both these hormones are involved with weight regulation. Insulin resistance, another symptom, is likely related to weight gain as well.

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Congestive Heart Failure

When the heart cannot pump efficiently, blood and fluid can accumulate within the body. This can cause swelling in the lower extremities and sudden weight gain. Many people become aware of their condition after noticing weight gain of over three pounds in a day or five pounds within a week. Other symptoms include shortness of breath, dizziness, and a general feeling of illness.

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