Many people believe their daily mug of coffee or other caffeinated drink helps them to lose weight or keep weight off. However, the diuretic effect of caffeine is what appears to create weight loss, and this causes loss of water, not fat. Reputable practitioners, like the Mayo Clinic, debunk the myth of caffeine for weight loss and discourage its use as a weight loss aid.

Caffeine intake often perpetuates many of the factors contributing to weight gain and continued obesity. Coffee and caffeine intake aggravates stress, including physical, mental, and emotional stress, leading to increased levels of the glucocorticoids including cortisol. A well documented relationship exists between chronically elevated levels of these stress hormones and deposition of excess fat in the abdomen leading to obesity as well as increased caloric intake, particularly increased ingestion of fats and sugars.

The following characteristics of coffee have an adverse effect on weight loss:

Coffee Elevates Stress Hormones

• Caffeine in coffee elevates the stress hormones cortisol, epinephrine (also known as adrenaline) and norepinephrine. These hormones are responsible for increased heart rate and blood pressure, and a sense of "emergency alert". Circulation of oxygen to the brain and extremities is decreased and the immune system is suppressed.
• The purpose of this "fight or flight" response is to provide the body with a temporary energy boost for intense physical activity. With today’s sedentary lifestyle, the continual state of increased stress resulting from caffeine consumption can negatively affect weight control through disruptions in normal metabolism.

Increased Cortisol Levels Lead to Abdominal Obesity

• Chronically elevated blood cortisol levels that are caused by frequent stress or regular caffeine or coffee intake lead to an increased buildup of fat in the abdominal area; this type of weight gain further stimulates the release of additional stress hormones.

Increased Stress Leads to Overeating

• This chronic state of increased stress caused by caffeine is associated with a markedly increased tendency to overeat. CNS stimulants stimulate anxiety and caffeine consumption increases the tendency of people to overeat or binge-eat and abuse laxatives and diet pills.
• Coffee drinking increases physiological measurements of stress, and although this effect is greater with increased caffeine levels.
• Elevation of stress hormones leads to fat cravings.
• Elevated levels of cortisol increase appetite.

Caffeine Stimulates Appetite

• Although caffeine is included as an ingredient in many weight-loss aids, it actually stimulates appetite, and organizations including the Mayo Clinic discourage the use of caffeine as a weight-loss aid. Initially, caffeine may decrease appetite through its central nervous system response. However, subsequently caffeine increases cortisol levels, and higher levels of cortisol stimulate appetite.
• Caffeine triggers hypoglycemia through the activation of the sympathetic nervous system and the adrenal glands, causing an immediate and sustained constriction of blood vessels, decreased circulation to the brain and a heightened feeling of low blood sugar. The body’s reaction to hypoglycemia results in food cravings and increased appetite. People often crave higher fat foods resulting in increased caloric intake, further interfering with the body’s ability to maintain a healthy weight.

Source: Meri Rafetto, RD, Theresa Grumet, RD, and Gerri French, RD, MS, CDE