Key Takeaways:

• The science behind weight loss is primarily based on the calorie balance equation: Calories In < Calories Out = Weight Loss.

• Rapid weight loss can have adverse effects on health, including muscle loss, nutritional deficiencies, and an increased risk of gallstones.

• The recommended and safe rate of weight loss is typically about 0.5-1 kg (~1-2 lbs) per week 

• A holistic approach, including exercise and realistic goal setting, is crucial for safe and effective weight loss.

• Personalized weight loss plans and consultation with healthcare professionals are essential for long-term success.

More than 1 billion people have obesity worldwide. Meanwhile, in Singapore,  the 2019/2020 National Population Health Survey by the Ministry of Health Singapore showed that 10.5% of residents in Singapore aged 18 to 74 years are obese.

Current trends suggest that these numbers are only expected to worsen in the coming years, which means that there needs to be a better understanding of the science behind weight loss.

The Mechanism Behind Weight Loss

The science of weight loss is rooted in the concept of energy balance. There’s nothing complicated about the mechanism behind weight loss. It is your calorie balance (i.e., how many calories you eat versus how many calories your body burns) determines your body weight. 

Therefore, if you eat:

• More calories than your body needs (i.e., surplus): Your body will store the excess calories as glycogen in your muscles and liver and fat in your adipose tissue. The result is an increase in body weight.

• Fewer calories than your body needs (i.e., deficit): Your body is “forced” to draw from its glycogen and fat stores for the energy it needs to function. The result is a decrease in body weight.    

• Here’s an important disclaimer. Saying that there’s nothing complicated about weight loss isn’t the same as saying it’s easy. The truth is that many people have trouble maintaining a calorie deficit long enough to lose weight successfully and, arguably more importantly, keep it off long-term.

Is it bad to lose weight too quickly?

If you have cracked the science behind weight loss, congratulations!

However, if your pants are getting too loose, too fast, you might need to step back a bit and re-examine your weight loss program. Is your diet plan too restrictive? Are you losing more than 0.5-1 kg (~1-2 lbs) per week?

Rapid weight loss may seem tempting, as you immediately see results. However, it raises an important question: Is it bad to lose weight too quickly? The answer is yes.

Losing weight too quickly lead to the following effects, among others:

• Muscle loss

• Hair loss

• Loose skin

• Slowed metabolism

• Nutritional deficiencies

• Increased risk of gallstone formation and cholecystitis

• Water and electrolyte problems

The Dangers of Rapid Weight Loss

Muscle Loss

One of the significant drawbacks of rapid weight loss is the potential loss of muscle mass. When the body undergoes extreme calorie restriction, it often breaks down muscle tissue for energy, especially when coupled with insufficient protein intake. The loss of muscle mass can lead to a slower metabolism, making it more challenging to maintain weight loss in the long run.

Gradual (not abrupt) weight loss that is combined with exercise gives your body time to lose fat while retaining your muscle mass. In terms of calories burned per session, aerobic exercise is generally more effective for weight loss than strength training. However, strength training has other benefits that can help you to lose weight and improve your overall health, such as increased muscle mass and improved metabolism.

The best approach for weight loss is to combine aerobic and strength training. Aim to do at least 30 minutes of moderate-intensity aerobic exercise 2-3 days of the week, and do two to three strength training workouts per week that target all of the major muscle groups.

Hair Loss

Rapid weight loss can cause temporary telogen effluvium, which is an excessive shedding of resting or telogen hair after metabolic stress, hormonal changes, or even medication. When a person goes through a crash diet or a restrictive diet, the metabolic stress on the body or deficiency in nutrients may cause hair loss.

Loose Skin

Losing significant weight really fast can lead to loose, saggy skin. Our skin consists of elastin and collagen, which are two essential proteins that give our skin its firm appearance, strength, and elasticity. It is the fibers in collagen and elastin that help skin stretch without tearing during weight gain and during growth. With rapid weight loss, it becomes more difficult for the collagen and elastin fibers to return to their original state – as they shrink and contract too quickly – resulting in loose, drooping skin.

Slowed Metabolism

The body is incredibly adaptable. When you lose weight rapidly, your metabolism may slow down as a survival mechanism. This means that as you lose weight, your body becomes more efficient at conserving energy, making it harder to continue losing weight.

Nutritional Deficiencies

A quick weight loss approach often involves severe dietary restrictions. This can lead to nutritional deficiencies, as you may not be getting the essential vitamins and minerals your body needs to function optimally. For example, Zinc, Iron, Vitamin B and D, and calcium deficiency can lead to an increased risk of developing health conditions such as anemia or unhealthy skin and nails; or may predispose you to injury. Additionally, it can also lead to lower immune function, low energy levels, and hair loss. A study evaluated four popular diet plans (Atkins for Life diet, The South Beach Diet, the DASH diet, the DASH diet). The results showed that all four diet plans failed to provide the minimum Recommended Dietary Intake (RDI) for adults.

Increased Risk of Gallstones

Rapid weight loss is associated with an increased risk of gallstones. Gallstones are hardened pieces of material that develop in your gallbladder.

When the body loses weight rapidly, the liver releases extra cholesterol into the bile which can cause the formation of gallstones. Rapid weight loss can also prevent the gallbladder from emptying properly. 

Dehydration

A significant portion of quick initial weight loss may come from water weight. While this can be motivating in the short term, it's not a sustainable or healthy way to shed excess weight. Dehydration can result in a range of health problems, including electrolyte imbalances and even organ damage in severe cases.

What is considered a safe weight loss rate?

Health and fitness experts generally recommend a rate of weight loss that is gradual and sustainable. According to the National Institutes of Health (NIH) and Centers for Disease Control and Prevention (CDC), a healthy weight loss rate is a gradual, steady weight loss of about 0.5 to 1 kg (~1 to 2 lbs) per week.

People who lose weight within this range are also more likely to keep the weight off than people who lose weight quickly. This approach is more likely to result in fat loss while preserving muscle mass and minimizing the risks associated with rapid weight loss.

The Optimal Approach to Weight Loss

Rather than focusing on the speed of weight loss, it's more important to adopt a holistic and sustainable approach. Here are some key principles for healthy and effective weight loss: 

Balanced Diet

A balanced diet is essential for providing your body with the nutrients it needs. Rather than following extreme diets, focus on consuming a variety of foods, including fruits, vegetables, lean proteins, and whole grains. Portion control and mindful eating are also crucial.

Regular Physical Activity

Incorporate regular exercise into your routine to boost calorie expenditure, preserve muscle mass, and improve overall health. Combining cardiovascular exercises, strength training, and flexibility exercises can enhance your weight loss efforts. If you are a beginner, here are some low-intensity workouts to get you started. 

Set Realistic Goals

Set achievable and realistic goals that consider your individual needs and circumstances. Sustainable weight loss is a long-term journey, not a quick fix. Remember that health should always be the top priority.

Consult Healthcare and Fitness Professionals

If you are considering a weight loss plan, consult with a certified healthcare or fitness professional, such as a registered dietitian, nutritionist, or a personal trainer. They can provide personalized guidance, tailor a plan to your specific requirements, and ensure that your weight loss journey is safe and effective.

A Tailored Personal Fitness Program to Help You Lose Weight Safely

NOVI PT Plus is a 1:1 tailored personal training program that includes continuous nutrition coaching to help you achieve your fitness goals – including losing weight safely.

This program is suitable for those looking to lose weight or gain muscle — even if you have chronic conditions, are on medications, or are new to PT.

The program helps through:

• Creating and guiding you through personalized exercise routines and dietary plans that prioritize your safety and well-being, while helping you achieve your goals.

• Holistic guidance and genuine care, using the NOVI Method. With our ongoing remote support, you will be motivated throughout the program.

• Data-based program adjustments to help you achieve your goals in a quicker time.

You can also book a trial session at $100 for 1 session