“Get a beachbody in 4 weeks!” “Lose the Christmas bulge by NYE” these supposed quick weight loss fads are everywhere.
It’s normal to want to lose weight as fast as possible.
However, losing weight too quickly with crash diets can lead to health risks (discussed below), and you’ll inevitably end up putting the weight back on. That’s why they’re called crash diets, you end up crashing and giving up. It’s not sustainable.
Multiple studies have shown that people who lose weight gradually over time, are likely to keep it off long-term, with fewer health risks (1, 2, 3)., particularly if you don’t have the support of a professional.
What Is Considered Fast Weight Loss?
The NHS and many other experts, recommend losing 1-2 pounds (0.45–0.9 kg) per week is a healthy and safe rate (4, 5, 6).
It important to note, that if you’re starting out on a diet or exercise plan, you may initially lose much more than 2 pounds in your first couple of weeks. This perfectly normal adaptation, is your body losing “water weight”.
When you consume fewer calories than your body burns, your body starts using stored energy called glycogen. The glycogen in your body is bound to water molecules, so when glycogen is burned for fuel, the body also releases water (7).
It is common for your weight loss progress to drop after this initial period of water loss and stabilise back to 1-2 pounds per week.
Risks of Losing Weight Too Fast
Following a diet that promotes very low calories to lose weight fast may sound appealing, but you may be putting yourself at risk of many health issues.
1. You May Lose Muscle Mass
While a big calorie deficit may help lose weight fast, a lot of this weight may not be fat, but rather muscle and water (14, 15).
As your body burns through stored glycogen, it also burns through muscle protein to convert into energy when you’re not feeding the body the amount of calories it requires.
Researchers put 25 people on a very low-calorie diet of just 500 calories per day for a period of 5 weeks. In another test group they has 22 people on a low-calorie diet of 1,250 calories per day for 12 weeks.
The study concluded that both groups lost similar amounts of weight. However, the people who followed the 500 calorie diet lost over six times more muscle than the group on 1,250 calories (16).
2. It May Slow Down Your Metabolism
Your metabolism determines the number of calories you burn per day. Several studies demonstrate that losing weight fast through calorie restriction can slow your metabolism down by up to 23% per day (8, 9, 10).
Two major causes of your metabolism slowing down on a low calorie diet are an imbalance with the thyroid hormone, which regulates your metabolism and a loss of muscle mass (11, 12). The impact on your metabolism and thyroid can last long after finish dieting (13).
3. Food cravings
Strict low-calorie diets which cause you to fight hunger, can lead to energy slumps and increase food cravings. When cravings get too bad, you may just fall of the wagon from one major binge that could wipe out all your progress – more seriously could trigger an emotional response or a disorder.
4. It May Cause Nutritional Deficiencies
If you’re not eating enough calories frequently, you may be missing out on essential vitamins and minerals, causing a nutritional deficiency.
Nutritional deficiencies can lead to wider consequences:
Extreme fatigue: A lack of vitamin B12 and folate can cause extreme fatigue and anemia (17, 18).
Poor immune function: Not getting enough nutrients can weaken your immune system and increase your risk of infections (19, 20).
Weak bones: A lack of vitamin D, calcium and phosphorus in your diet may lead to weak and brittle bones (21, 22).
Going on a crash diet to lose weight fast has also been linked to other side effects, including (23, 24):
- Dizziness
- Irritability
- Dehydration
- Muscle Cramps
- Feeling Cold
- Constipation
- Diarrhoea
A better approach
Slow and steady weight loss doesn’t make the glamour magazines, but it has less health risks and it’s sustainable.
Here are a few things you can do to help speed up the process safely.
Cut down processed foods: Swapping out processed refined foods for complexed carbohydrates like whole grains, brown rice and vegetables can help stabilise your blood sugar level and insulin for optimal weight loss.
Eat more protein: Consuming more protein can boost your metabolism, prevent muscle loss and keep you fuller for longer (27, 28, 29).
Eat soluble fibre : Researchers have found that soluble fibre may help burn fat, especially belly fat, and support weight loss (30, 31).
Develop new behaviours: building new skills like mindful eating, eating more slowly, being aware of your food choices and how you feel after eating can help you keep weight off long-term.
References
1 – https://www.ncbi.nlm.nih.gov/pubmed/1615884
2 – http://onlinelibrary.wiley.com/doi/10.1002/oby.21925/full
3 – https://www.ncbi.nlm.nih.gov/pubmed/11972741
4 – http://www.nhs.uk/Livewell/loseweight/Pages/should-you-lose-weight-fast.aspx
5 – https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0063069/
6 – https://www.nhlbi.nih.gov/health-pro/resources/heart/aim-facts-html
7 – https://www.ncbi.nlm.nih.gov/pubmed/1615908
8 – https://www.ncbi.nlm.nih.gov/pubmed/2204100
9 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4989512/
10 – https://www.ncbi.nlm.nih.gov/pubmed/23404923
11 – https://www.ncbi.nlm.nih.gov/pubmed/3812338
12 – https://www.ncbi.nlm.nih.gov/pubmed/22516719
13 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4989512/
14 – https://www.ncbi.nlm.nih.gov/pubmed/1615908
15 – http://onlinelibrary.wiley.com/doi/10.1002/oby.21346/full
16 – http://onlinelibrary.wiley.com/doi/10.1002/oby.21346/full
17 – https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0022011/
18 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1297139/
19 – https://www.ncbi.nlm.nih.gov/pubmed/9250133
21 – https://www.ncbi.nlm.nih.gov/books/NBK45504/
22 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3012634/
23 – https://www.ncbi.nlm.nih.gov/pubmed/25586973
24 – https://www.ncbi.nlm.nih.gov/books/NBK278991/
25 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC538279/
26 – http://www.nejm.org/doi/full/10.1056/NEJMoa022207
27 – https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-11-53
28 – https://www.ncbi.nlm.nih.gov/pubmed/25926512
29 – https://www.ncbi.nlm.nih.gov/pubmed/18469287
