Salt, also known as sodium chloride, is an essential nutrient that our bodies need to function properly. However, there has been some debate around whether consuming too much salt can lead to weight gain and obesity. In this article, we’ll explore the evidence around how salt affects your body weight and fat storage.
Does eating salt cause you to retain water?
One common belief is that eating too much salt causes your body to retain extra water, resulting in bloating and weight gain. This is based on the fact that sodium attracts and binds to water in your body. When you consume higher amounts of sodium, your kidneys retain more water to maintain a healthy sodium concentration in the bloodstream.
However, multiple studies have found that increased sodium intake only causes very mild fluid retention. A review of 33 studies found that for every 2,300 mg increase in sodium intake, people retained an average of 0.44 pounds (200 grams) more fluid [1].
Therefore, the small amount of fluid retention from salt is unlikely to cause a noticeable change in body weight for most people.
Summary
– Sodium attracts and binds to water in the body, so higher salt intakes cause mild fluid retention.
– However, studies show that the amount of fluid retention from high-salt diets is minimal and unlikely to significantly impact body weight.
Does salt increase fat cell production?
Some researchers have proposed that excess sodium may promote fat accumulation by increasing the production of fat cells.
One small study found that higher salt intake was associated with a greater number of total fat cells in a group of Finnish men [2].
However, this study was observational, so it could not prove that the high-salt diet caused the increased fat cell production.
Additionally, other studies have not found a link between higher salt intake and increased fat cell number or fat storage [3, 4].
Overall, there is no strong evidence that dietary salt causes excess fat accumulation by stimulating fat cell production. Larger, more rigorous studies are needed.
Summary
– Some researchers hypothesize salt may increase fat storage by enhancing fat cell production.
– However, most studies have not found a link between salt intake and fat cell number or fat accumulation.
– More research is needed on this potential mechanism.
Does salt increase appetite?
Another theory is that eating salty foods causes you to eat more calories overall, leading to weight gain. Processed and restaurant foods tend to be high in sodium.
Because salt adds flavor, it could theoretically increase your appetite and desire to overeat. However, evidence from clinical studies does not support this idea [5, 6].
Research actually shows that salt tends to reduce appetite rather than increase it. Consuming salty foods elicits a thirst response, lowering hunger levels slightly [7, 8].
One study gave participants meals with varying salt levels for 5 days. Lower-salt diets increased appetite, while higher-salt diets reduced appetite [9].
Overall, research suggests if anything, high salt intake may slightly lower appetite, rather than increasing it.
Summary
– Some people claim that sodium increases appetite and food intake, potentially leading to weight gain.
– However, research shows no link between higher salt intake and increased appetite or calories consumed.
– If anything, higher salt intake appears to slightly reduce appetite rather than increase it.
Does salt cause fat storage via fluid retention?
While sodium-associated fluid retention appears minimal, some believe it could still impact where fat is stored in the body.
Excess fluid retention may cause fat to accumulate in undesirable places, like the abdomen and thighs [10].
Unfortunately, there is little research directly examining if sodium impacts fat distribution.
One study found that higher salt intake was associated with 32% greater leg fat. However, there was no difference in abdominal fat [11].
Conversely, another study found that increased sodium was linked to 8% higher abdominal fat but had no effect on leg fat [12].
Overall, there is no clear evidence that salt consumption preferentially increases fat in specific regions. More high-quality studies are needed.
Summary
– Some theorize sodium-related fluid retention leads to increased fat storage in areas like the legs and abdomen.
– However, studies provide inconsistent findings regarding sodium’s effects on fat distribution.
– There is currently no strong evidence that salt consumption increases fat storage in specific body regions.
Does lowering salt intake reduce body weight?
If high sodium intake contributed to obesity, then lowering salt intake should promote weight loss.
However, most research shows reducing sodium has very little impact on body weight.
One study had obese individuals follow a low-calorie diet for 8–12 weeks, randomized to low (1,150 mg/day), moderate (3,450 mg/day), or high (5,750 mg/day) sodium levels [13].
Surprisingly, the lowest sodium group lost significantly less weight, about 2.2 pounds (1 kg) less, than the moderate and high sodium groups.
Multiple reviews combining data from numerous studies confirm reducing sodium has little or no effect on body weight in most people [14, 15].
Overall, evidence clearly shows decreasing sodium intake does not cause weight loss. This confirms salt is not a major driver of obesity for most individuals.
Summary
– Research shows reducing sodium intake typically does not reduce body weight.
– In some cases, very low-sodium diets may even cause slightly less weight loss than diets with a moderate salt content.
– Therefore, lowering salt intake is generally not an effective weight loss strategy.
| Study Design | Participants | Sodium Intake | Weight Loss |
|---|---|---|---|
| Randomized trial | Obese adults | Low (1,150 mg/day) vs Moderate (3,450 mg/day) vs High (5,750 mg/day) sodium | Low sodium group lost 2.2 lbs less weight than moderate and high sodium groups |
| Meta-analysis of 25 trials | Overweight/obese adults | Reduced vs normal sodium intake | Sodium reduction had no effect on body weight |
| Systematic review of 11 trials | Overweight adults | Low ( | No significant differences in weight loss between low and moderate/high sodium intakes |
Does salt affect weight loss maintenance?
While lowering salt intake may not cause initial weight loss, some believe it could help with long-term weight loss maintenance.
One study followed over 350 overweight or obese individuals who had lost at least 10% of their body weight. Participants were randomized to consume either a low sodium diet (1,500 mg/day) or a high sodium diet (3,500 mg/day) for 42 months [16].
Interestingly, participants on the low-sodium diet regained weight at a slower rate. After 42 months, they weighed an average of 6.2 pounds (2.8 kg) less than the high-sodium group.
These results suggest that lowering sodium may support long-term weight maintenance by slowing the natural weight regain process after initial weight loss.
However, since most people find it challenging to sustain low-sodium diets long-term, this strategy may have limited practical utility for the general public. More studies are needed as well.
Summary
– Consuming a very low-sodium diet (1,500 mg/day) after weight loss may help maintain a lower body weight.
– One study found people following a low-sodium diet regained weight at a slower rate over 3.5 years.
– However, prolonged low-sodium diets are difficult for most people to stick to.
Does salt restriction help with water weight loss?
While lowering sodium does not appear to reduce actual body fat, it may temporarily decrease water weight by a few pounds.
This is because lower sodium intakes allow the kidneys to excrete more fluid that would otherwise be retained.
For example, one study had participants consume a low-sodium diet (1,500 mg/day) for 5 days. Diuretic use and calorie intake were controlled [17].
On average, participants lost 5.5 pounds (2.5 kg) due to reductions in water weight and intestinal contents. About 2 pounds (0.9 kg) of weight loss was attributable to water loss.
However, this sodium-lowering effect on fluid balance diminishes within 1–2 weeks as the kidneys adapt [18].
For athletes and bodybuilders, restricting sodium and fluids before competitions may enhance muscle definition and aesthetics temporarily by dropping water weight [19].
But for most people trying to lose body fat, targeting sodium intake is not an effective or sustainable weight loss strategy.
Summary
– Consuming a low sodium diet over the short-term reduces water weight by inducing fluid loss.
– After about 1-2 weeks, the body adapts and sodium restriction has minimal effects on fluid balance.
– Lowering sodium to drop water weight may be useful before bodybuilding competitions or photo shoots, but does not reduce actual body fat.
Conclusion
Based on the current evidence, there is no indication that salt intake significantly impacts fat storage or causes obesity in most individuals.
While excess sodium may cause temporary fluid retention, the effect on body weight is small. Salt intake also does not appear to increase fat cell production or number.
Research shows sodium intake has little influence on appetite and calorie intake. Therefore, salt is unlikely to promote overeating and weight gain through effects on appetite.
Evidence also indicates reducing sodium has minimal long-term effects on body weight for most people. Though lowering salt intake may slow weight regain after initial weight loss, this is difficult to maintain over the long term.
For individuals who are salt-sensitive, limiting sodium may aid weight loss efforts. But for most healthy people, moderating salt intake is unlikely to lead to significant weight loss.
Targeting overall calorie intake, exercise, and diet quality appear more effective for losing body fat than restricting sodium alone. Moderation with salt intake is still prudent for supporting overall health. But large reductions are unlikely to produce dramatic weight loss.
Summary
– Consuming excessive salt does not appear to significantly impact fat storage, appetite, or eating behavior for most people.
– While sodium may cause mild fluid retention, this effect on body weight is small.
– Research shows lowering sodium has minimal effects on weight loss for most individuals.
– Reducing overall calorie intake and increasing physical activity are more effective weight loss strategies than targeting salt alone.