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Increased Dietary Salt May be Correlated with Obesity

Consuming more salt, regardless of caloric consumption, can lead to obesity or being overweight. A study in the journal Hypertension reports that an increased intake of 1 g of sodium per day increases the risk of obesity by 28% in children and 26% in adults. In the UK and the United States, the recommended daily intake of sodium is 2,300 mg (which correlates to 6 g of salt). It is important to note the distinction between sodium and salt: sodium is the electrolyte represented by the symbol Na, whereas salt (or table salt) is the combination of sodium and chloride. It is 40% sodium by weight.

The mechanism by which increased sodium exerts weight gain is unknown, but is likely related to fat metabolism changes. Increased weight gain is a risk factor for other disease states, like hypertension and type 2 diabetes. These diseases lead to severe complications.

This finding is disputed by some in the healthcare industry. A dietitian at St. George’s Hospital NHS Trust, Catherine Collins, believes this to be a fallacy related to misunderstanding of correlation and causation. She says that increased dietary salt intake is related to increased caloric intake in general. Therefore it is a marker of obesity, but not a cause.

The claims of this finding are further disputed because caloric intake was self-reported by the study participants. Susan Jebb, a diet professor at the University of Oxford, thinks that this study may mislead people into thinking that reducing salt intake is a simple enough solution to reduce weight gain. Instead, people should focus on caloric reduction, eating healthier, and becoming more physically active.

More research needs to be done into this take. Future studies may investigate the effect of sodium on fat metabolism. In addition, if caloric intake becomes an objective rather than a subjective measure by allowing the study’s clinicians to measure it instead of having patients self-report it, it can be verified whether increased salt intake itself is really a risk factor for weight gain independent of caloric intake.

Practice Pearls:

  • Increased dietary salt intake is a risk factor for cardiovascular disease. One study claims that it is also a risk factor for being overweight.
  • It is suspected that sodium has an effect on fat metabolism, explaining the weight gain. Some clinicians question the study, however, and think that sodium intake is correlated with increased caloric intake in general, leading to weight gain.
  • Patients should not think that reducing sodium intake alone will reduce their risk for obesity or cardiovascular or metabolic complications. Healthy diets, reduced caloric intake, and increased physical activity are all necessary lifestyle changes as well.

Published in the journal Hypertension, Aug 2015.