What causes rapid weight gain?

Rapid unexplained weight gain can happen to anyone. It can be due to one of these five unexpected causes.

It should be considered that weight can fluctuate during the day and it is common to experience weight gain over time.



But what causes rapid weight gain and how can it be detected? This blog post looks at the causes of weight gain.

What causes rapid weight gain?

Common causes for weight gain which are not related to medical conditions are:

Increase in food consumption: According to the NHS ‘most people put on weight because they eat and drink more calories than they burn through every day and movement and body functions’. The European Association for the Study of Obesity reported in 2009 that the rise in obesity since the 1970’s was almost exclusively caused by an increase in calorie intake.

Reduced physical exercise: A reduced amount of exercise is seen as the main reason weight gain occurs as we get older. Some calories are burned while we eat, but the majority of energy expenditure occurs during and after exercise, known as physical-activity expenditure and post-exercise oxygen consumption. As we get older, we exercise less.

Water retention: Unexplained rapid weight gain may be the result of fluid retention which can cause your limbs, hands, feet or face to look swollen - according to Healthline.

Stress, depression and anxiety: Weight gain can be a symptom of anxiety - but anxiety doesn’t always cause weight gain. The stress hormone cortisol is the key reason why people with anxiety have trouble managing their weight. Cortisol is released during times of stress, and causes fat to build up. Stress and anxiety can lead to excess eating. People find that food provides a valuable coping tool and some people experience greater hunger when stressed.

Lack of sleep: Rapid weight gain can be caused by sleep deprivation. Research from the University of Colorado found that one week of sleeping about 5 hours per night led to participants gaining an average of 2 pounds (0.9kg). Sleep deprivation causes changes to hormones that regulate hunger and appetite. It can also affect food craving, stipulating in more intense cravings for fat and sugar-laden foods. People may also turn to food if they cannot sleep.

Meal times: A recent study has shown growing evidence between eating later in the day and weight gain. Earlier studies have identified a pattern between eating later and increased weight gain, with “calorie intake after 8pm increasing the risk of obesity.” Those who ate later in the day had a higher BMI and greater levels of body fat. The research also showed that those who ate later in the day still had an average of 7 hours sleep, which implies lack of sleep is not the primary driver of these effects.

Medical reasons for weight gain

As well as the reasons above, rapid weight gain can be caused by medical reasons, highlighted by the NHS.

Underactive thyroid: This means your thyroid gland is not producing enough thyroid hormones - which plays a central role in regulating metabolism. “Without enough thyroid hormone, the body’s metabolism slows down, which can lead to weight gain,” says dietitian Catherine Collins.

Diabetes treatment: A common side effect for people who take insulin to manage diabetes is weight gain. Insulin helps to control blood sugar levels, with some people with diabetes tending to eat more than they need to prevent low blood sugar level.

Ageing: People begin to lose amounts of muscle as they get older and become less active. A loss of muscle mass can mean you burn fewer calories.

Steroid treatment: Steroids, known as corticosteroids, are used to treat a variety of conditions. Long-term use of corticosteroid tablets can increase appetite in some people. “Steroids make you feel hungry as they affect areas of the brain that control feelings of hunger and satiety,” says Collins.

Polycystic ovary syndrome (PCOS): This is a common condition that affects how a woman’s ovaries work. The cause of PCOS is unknown, but it is thought to be hormone-related, including too much insulin and testosterone. “Women with PCOS typically put on weight around their waste. The more weight you put on, the more insulin you produce, which can cause further weight gain,” said Collins.

Regular weighing helps prevent weight gain

Weighing regularly can prevent weight gain, according to experts at the University of Birmingham and Loughborough. The research compared two groups - one that was instructed to record their weight and one that was not - in a goal to not gain weight.

The group that was not recording their weight gained 0.37kg on average during the study; those that were recording weight lost 0.13kg.

To reduce the obesity epidemic, the government has also recommended patients are “weighed by default” when visiting a GP.

Suitable weighing scales

Scales for home use

Marsden M-550: The M-550 is an affordable, accurate professional medical floor scale, used by GP surgeries but is also suitable for home use. It is Marsden’s lowest priced Class III Approved medical scale. Amateur runner Matt Smith uses the M-550 at home to monitor his ‘fastest weight’. Read more here.

Scales for gyms, sports clubs and personal trainers

Marsden M-150: This robust column scale is an affordable, easy to use scale suitable for gyms, sports clubs, leisure centres and spas. It has a BMI function and weight readings can be shown in kg/g or st/lb.

MBF-6010: Weight gain does not always mean a rise in body fat, and that is why a body composition scale is useful. Marsden body composition scales can calculate Basal Metabolic Rate (BMR), Total Body Water (TBW), Fat Free Mass (FFM), Fat Mass (FM), Body Fat Percentage, Muscle Mass (MM), Protein Mass (PM), Extracellular Water (ECW), Intracellular Water (ICW), Skeletal Muscle (SM), Visceral Fat Area Level (VFA), Metabolic Age (AGEM), Weight and BMI.  Marsden body composition scales are closer to DEXA standard than any other scale according to this report on The One Show. This MBF scale is column-mounted so is a more permanent fixture and is widely used in hospitals, gyms and sports clubs.

Scales for GPs

Marsden M-420: This floor scale weighs in increments to 50g, below 150kg. It is robust, easy to use and is portable. The tap-on function switches on the scale without the need to bend down. The Hold function means the reading stays fixed to the screen after the user steps off the scale. Along with the M-550 and M-430, the M-420 is ideal for weighing patients in a GP surgery.

Marsden M-125: This scale features a column-mounted indicator, 100g accuracy and capacity to 250kg. An optional height measure and BMI calculation function mean BMI can be easily found. There's an optional height measure and the scale can be used to calculate BMI.

For more information on any of our scales, call 01709 364296, contact us here or via our web chat facility.

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