Everything You Need to Know About Losing Weight Fast

It’s very easy to be impatient once you’ve decided to start a weight loss journey - you’re eager to see results, hit your goals and lose weight as fast as you possibly can. There are countless diet and exercise programmes claiming to offer the quickest way to lose weight, but just how achievable, effective and, most importantly, healthy is fast weight loss?

Is fast weight loss healthy?

It’s important to start by noting that everyone’s bodies, goals and processes are different, and what works for one person may not be right for someone else. Similarly, a healthy approach for one individual isn’t necessarily the same across the board. A heavier person who’s carrying more fat, for example, might expect to lose weight more quickly than a person who’s just trying to shift a few pounds.
How healthy weight loss is often depends on the methods you’re using and just how fast you’re slimming down. If you’re still eating a healthy amount of calories and ensuring your nutrition is balanced, and if you’re undertaking a workout program that’s challenging without exhausting yourself and your body, then your weight loss is likely to be healthy. If, however, you’re dramatically below your recommended calories, you might be losing weight quickly, but in a less healthy way that could have a damaging effect on your body.

What are the risks of losing weight too fast?

Losing weight too fast can carry some risks, such as:
Unsustainability
Putting your body through an intense diet and workout regime to lose weight very quickly can be extremely difficult to keep up over time. It’s less of a lifestyle change and more of a quick fix. Crash diets in particular can be very unsustainable, risking regaining the weight you lost once you return to your regular eating habits.
Electrolyte imbalance
This is when the food you consume isn’t providing you with the right balance of electrolytes (for example, salt, potassium, chloride, magnesium and phosphate). These are key components in your body that help with vital processes such as your immune system, blood glucose levels, blood pressure, bone health, digestion, and muscle and nerve functions. While it’s natural for electrolyte levels to fluctuate, consistently toying with the balance your body needs to function could lead to issues such as cramping, fever, breathlessness, fatigue, confusion, headaches, irregular heartbeats and convulsions.
Malnutrition
As with electrolytes, a nutritionally well-rounded diet keeps your body fuelled with all the nutrients, vitamins and minerals it needs to stay fit, healthy and happy. If you’re majorly restricting your diet then you are very likely missing out on key nutritional benefits and could face the symptoms of deficiencies. For example, cutting carbs could mean you’re not getting enough fibre (which can result in constipation, nausea or blood sugar fluctuations) or completely removing dairy from your diet could mean a calcium deficiency (which can lead to brittle bones and even osteoporosis). It’s worth considering your diet changes carefully and finding alternative sources to provide your body with enough energy and nutrients to thrive.
Decreased muscle mass
When you lose weight too quickly, sometimes the body turns to muscle mass for fuel. So while you’re technically lowering the number on the scales, you’re actually losing vital muscle mass. Muscle isn’t just essential for keeping your body moving effectively and looking toned; it’s also more metabolically active than fat, helping to burn more calories.
Fatigue
Stripping your body of the nutritional energy it needs, particularly if paired with intense exercise, can lead to exhaustion and fatigue. You may struggle to make it through the working day without feeling extremely tired. When your body’s fatigued it may crave high calorie foods, or be less inclined to head to the gym, creating a cycle that’s both erratic and unhealthy.
Low mood or irritability
If you’re exhausted from pushing yourself in the gym without the right nutrition to maintain your energy levels, you could find yourself not just undoing the fantastic mood-boosting effects of exercise, but actually feeling more stressed, grouchy or emotional. Fatigue and hunger can lead to low moods, which in turn can leave you feeling too lethargic to focus or find motivation.

Can rapid weight loss be good for you?

But is losing weight quickly just a totally unhealthy approach? Can it be a positive part of a wellbeing journey? The truth is, yes it can be, but again it really depends on your body type and health goals.
Some people have much faster metabolisms than others and may find the weight loss process happens quicker as a result. Often those just starting out with healthy eating and exercise will lose weight at a higher rate initially (usually in the first couple of weeks) as their body adjusts to the new routines and releases water weight. This will usually then slow down to a more regular rate of loss as these changes become a more regular part of their lifestyle.
It’s not necessarily the speed of weight loss that can be unhealthy (unless you don’t need to lose weight, or are losing weight due to ill health), but the process by which you’re achieving it. While focusing on losing weight, it’s important to consume a well-rounded, healthy diet that supplies your body with the energy, fuel and nutrition it needs to function effectively. If you’re doing this, and including a thought-through exercise programme, then you’ll most likely be losing weight in a healthy way.
If you have concerns that you’re losing weight too fast, it might be worth speaking to your GP or a nutritionist to ensure you’re taking the correct approach.

How Many Calories Do I Need to Eat to Lose Weight?

General recommendations for weight loss is to aim for a calorie deficit of around 500 - 1,000 below your TDEE, depending on how high your daily calorie burn is. This will ensure that you’re consuming less calories than you use and your body will ideally start to burn your existing fat reserves to fill the energy gap. Don’t be tempted to drop your calories too low - it’s widely recommended that most people consume a minimum of 1,200 calories a day to ensure the body has all the nutrients and energy it needs to thrive and function.
It’s important to remember that less isn’t always better, and that definitely applies when thinking about how many calories your body needs. Calories are fuel for your workouts and help your body to stay strong, recover well and function properly. If your calories are too low you may find you can’t put as much effort into your workouts, which plays a huge role in losing weight and getting fitter.
There are a variety of apps and websites that will be able to provide specific calorie recommendations for your activity level, body shape and goals. As a very loose guideline, the general recommended daily calorie intake for men is 2,500 and for women is 2,000. If you’re fairly inactive, a healthy target for weight loss would be around 1,300 - 1,500 for women and 1,800 - 2,000 calories for men. If your activity levels are higher, you may want to be raising this figure to account for around half the calories you’re burning through exercise.

How Can I Tell How Many Calories Are in My Food and Drink?

Any packaged goods you pick up from the supermarket will have their calorie counts marked on the wrapper or container. By keeping track of these, you can gain an understanding of how many calories you’re consuming on a day-to-day basis. For items like a pre-packaged lunchtime sandwich, drink or salad bowl, these will usually show the full calorie count in a table on the front or back. If, however, you’re making your own meal using multiple ingredients, you’d need to tally up the calories for each item (e.g. each slice of bread plus each item of filling and garnish).
For non-packaged items, you can usually find calorie checkers online (such as this one from the NHS), or use specific meal tracking apps such as MyFitnessPal. If you’re dining out, many chain restaurants list their nutritional information on their website, or you can often work out an estimated calorie count based on the ingredients used in the meal.