5 Evidence Based Side Effects Of Sudden Weight Loss

Obesity or overweight is a healthcare problem affecting 600 million people worldwide.

Obesity gives way to certain healthcare problems in our body like type 2 diabetes, high level of cholesterol and glucose in the blood, cardio-vascular diseases, hypertension etc.

The primary cause of obesity is our sedentary lifestyle and lack of physical activity.

Gradually it has become a potential lifestyle problem.

The only solution of which is gradual weight loss. This weight loss can be achieved either by medication or by proper diet and exercise.

But do not miss out on the fact that we are talking about gradual weight loss. Sudden weight loss or rapid weight loss can cause health risks.

Sudden weight loss can lead to certain side effects like lowered immunity, increased level of the hunger hormone, gall bladder stone etc., if not checked properly.

5 Evidence-Based Side Effects of Sudden Weight Loss

Gradual weight loss involving fat loss but maintaining muscle mass is healthy weight loss. But sudden weight loss can take a toll on your health. Here, we deal with the potential side effects of weight loss, as revealed by research.

1. Unmonitored weight loss increases appetite

A major side effect of sudden weight loss is an increased feeling of hunger in some people leading to overeating. This is due to the increased level of the hunger hormone, ghrelin.

More or less we all know what it feels like to be on crash diets; the more we restrict ourselves the more we feel hungry and the more we binge.

Ghrelin expression is responsible for our hunger. Weight loss often triggers an over-expression of this hormone.

A 6month trial on 8 obese women bore evidence of this effect. It showed reversible suppression of ghrelin expression in obese patients.

A 12% increase in ghrelin level is reported in case weight loss and this concentration varied according to the extent of weight loss.

A study was undertaken to assess the role of hormones associated with obesity in children (pre-puberty). It was found that ghrelin levels were low in these obese individuals prior to weight loss. Weight loss triggered a higher level of ghrelin.

A 6-12months follow up study after a laproscopic surgery as a treatment for weight loss showed similar results.

In this case, long term weight loss was shown to correlate with an increased level of ghrelin.

This increase in ghrelin level was co-related with a decrease in insulin concentrations.

Here is one contradicting report, a 4-week study showed weight loss and subsequent maintenance of it didn’t lead to any change in ghrelin levels.

What does this mean? Despite some contradicting results there are ample evidence which shows that sudden weight loss can cause rise in ghrelin level and this can stimulate appetite.

2. Sudden weight loss may weaken the immune system

Weight loss has some adverse effects on the immune system of our body leading to decreasing immunity.

This decrease in immune function is primarily because of reduction in certain components – essential immune cells of the immune system

A 5 year follow up cross-sectional study on 114 obese women illustrated this effect.

According to this study weight loss reduces the number and immunological function of the Natural Killer Cells (a type of immune cells) which might decrease immunity.

A 10-pound weight loss triggered potential low levels of NK cells activity as compared to individuals without weight loss.

An 8-week long study involving 22 obese women bore similar results. In this case, NK cells activity decreased during weight loss.

In case of diet-induced weight loss, it showed significant decrease whereas in case of diet plus exercise-induced weight loss it remained unaltered.

Another 12-week study with 13 obese individuals shows a reduction of immune cells as a result of weight loss.

This study showcased even moderate level of weight loss (1.4 kg ) results in the reduction of T lymphocyte, B lymphocytes, monocytes, and granulocyte function.

Both T and B lymphocytes are an essential part of the immune system. Any dysfunction in them will lead to an adverse effect.

What does this mean? From the above evidences it is clear that weight loss can lead to decreased immune function by suppressing the activity of some of the immune cells. Sudden weight loss decrease immunity and increase susceptibility to infection and flu.

3.Weight loss trigger loss of lean muscle mass

Often when we lose weight, we lose muscle on the process.

This causes reduced body strength. Hence it is essential to monitor that weight loss and to check whether we are losing fat or muscle.

This is due to low protein intake and can be rectified by a high protein intake during weight loss.

A 20 week randomized trial in obese women showed low-calorie intake and weight loss. The energy intake was much lower in the diet plus exercise group than the diet-only group.

An average weight loss of 4kg was coupled with 32% average loss of lean muscle mass.

Further analysis showed participants with higher protein intake had lower loss of muscle mass.

A 4 week study on 20 athletes showed some evidence to this point. Athletes were given 15% and 35% protein rich diet during this period.

The results showed that greater level of protein intake reduced the lean muscle mass loss during weight loss.

Another study on 30 obese patients showed exercise along with diet attenuates the lean muscle mass loss during weight loss.

The lean muscle loss was higher in the group with a diet regime and lower in the diet plus exercise regime of weight loss.

What does this mean? Unmonitored weight loss is often associated with muscle loss. Thus resulting in loss of strength and feeling fatigue. This can be rectified by incorporating protein rich food items in our diet.

Side Effects Of Weight Loss

4. Sudden weight loss may lead to gall stone formation

Obese people are at higher risk of developing gall bladder stones. This is due to higher cholesterol level in bile resulting in gall stone formation.

Thus, weight loss should be beneficial in this regard.

But it isn’t true for all cases. Drastic weight loss can lead to gall stone formation. It is one of the side effects of weight loss.

This is an effect is due to the release of cholesterol in bile caused by fat decomposition.

The reason behind this is inadequate time for the gall bladder to react on the decomposed products.

This is often caused in cases of low diet-induced weight loss and surgical weight loss.

Analysis of data from different perspective studies highlights this point.

There is a 15-20 fold increased risk of gall stone formation in the first 4 weeks of weight loss as compared to obese people risk.

A 6months trial on low-calorie diet-induced weight loss bore similar results.

54.5% of people in the low-fat diet group showed gall stone symptoms whereas none in the high-fat diet group suffered from gall stones.

This study highlights rapid weight loss in the initial stage of diet-induced weight loss can trigger gall stone formation.

An 8 week trial with low-calorie food diet vindicated this effect. Participants were under 2 regimes – one on a diet of less than 2g daily fat intake and another on a 30 g daily fat intake.

Both showed significant weight loss.

However, the gall bladder emptying capacity was 35% in the less than 2g fat group and maximum in case of 30g fat group.

Thus, the group with greater weight loss had a larger risk of gall stone formation than with the group less weight loss.

A study showed that the gallstones caused by surgery-induced weight loss can be prevented by daily intake of 600mg of ursodiol ( a chemical bile acid).

What does this mean? Drastic weight loss at the initial stage increases the risk of gallstone formation by lowering gall bladder emptying capacity. Inclusion of dietary fat within permissible limits can help offset this effect.

5. Weight loss can lead to loss of bone density

Weight loss is associated with loss of bone mass and bone density like that of lean muscle mass.

Drastic weight loss causes low bone density and lone bone mass.

On the contrary controlled moderate weight loss doesn’t cause such an adverse effect. This is can be rectified by incorporating calcium and Vitamin D in our diet.

A year-long prospective study on 67 obese women highlighted this effect.

Results from this study showed weight loss lowered bone mineral density and increased osteocalcin (a protein found in bone) in blood.

This reduction in bone density is correlated with weight loss and thus varied according to the extent of weight loss.

Meta-analysis from various trials of 3 -24 months duration showed reduced bone density in the initial time of weight loss.

The initial months that is 6months showed reduced bone density and increased osteocalcin level in blood.

However, no such effects were seen after 24 months. It suggested weight loss at the initial stage triggers bone break down in the hip region.

What does this mean? Some evidence points that weight loss can lead to bone mass loss due to lack of Calcium and Vitamin D. This can be countered by introducing Calcium, Vitamin D rich diet during weight loss.


Drastic weight loss or weight loss involving both losses of muscle and fat mass can have side effects.

However, these side effects can be easily prevented by closely monitoring the effects of weight loss and taking adequate steps in case of adverse symptoms.


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