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Top 25 Science-Backed Ways to Lose Weight Fast

Written by Joe Cohen, BS | Last updated:

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how to lose weight fast

Do you struggle to lose weight, even on the strictest diets? Read on to learn surprising lifestyle hacks that can help you reach your goals.

How to Lose Weight Fast

1) Eat Within a 12 Hour Window

Caloric intake after 8:00 PM increases the risk of obesity, independent of sleep timing and duration [1].

In addition, eating in the evening or before sleep predisposes individuals to weight gain through higher total calories [2].

2) Get More Sun – in the AM

UV decreases obesity in animals, independent of vitamin D status [3].

In addition, Vitamin D deficiency is also suspected to be a cause of obesity [4].

Intense light exposure, particularly in the morning, is associated with a lower BMI independent of sleep duration and timing [5].

Having a majority of the average daily bright light exposure (above 500 lux) earlier in the day was associated with a lower BMI [5].

In particular, red and green light exposure in the morning for two hours immediately upon waking in sleep-restricted (5 hours/night) individuals altered the levels of the satiety hormones, leptin, and ghrelin. Specifically, red and green light increased leptin and decreased ghrelin [6], both of which cause reduced hunger following sleep deprivation.

Exposure to at least 45 minutes of morning light (between 6 – 9 am at 1,300 lux) for 3 weeks in obese women resulted in reduced body fat and appetite [7].

3) Block Out Blue Light At Night

Increased light exposure has been associated with obesity in both humans and mice [8].

Blue light at night can cause weight gain [9, 8].

For every hour later of bright light, there was a 1.28 unit increase in BMI [5].

Light exposure in the in the evening changes the timing of slow wave sleep and reduces rapid eye movement sleep [10], and reduced slow wave sleep have been shown to worsen metabolic function [11].

Even dim light at night disrupts the circadian clock and increases body weight [9].

Studies have shown that 35% of the variance in BMI is caused by light exposure – in particular at night [5].

Prolonging daily light exposure increases obesity by decreasing energy expenditure rather than increasing food intake or activity [8].

This was caused by a light-exposure period-dependent reduction of the noradrenergic activation of brown fat tissue that has recently been shown to contribute substantially to energy expenditure by converting fatty acids and glucose into heat [8].

It’s critical to wear blue blocking glasses for four hours before bed.  Make sure to use black tape to cover any electronics that emit blue or green light and put your shades down at night if light is coming in.

4) Get More and Better Quality Sleep (at least 8 hours)

Short sleep duration is independently associated with weight gain in many studies [12, 5].

Short sleep duration raises the risk of obesity by 89% in children and 55% in adults [13].

Poor sleep can increase hunger and cravings and disrupt hunger hormones like ghrelin and leptin [14, 15].

If your quality or quantity of sleep is bad, everything else will be out of whack.

If you’re waking up in the middle of the night, that’s bad news.

Fix your sleep:

5) Take Cold Showers

This means take cold showers, wear an Ice Helmet/Cryohelmet, use fewer layers, etc. You should make sure you’re shivering daily, multiple times in the day. If you don’t see goosebumps at least a few times in the day, you’re not cold often enough.

Cold increases metabolism and increases energy expenditure (by increasing brown fat).

Men exposed to a cool environment overnight for a month had an increase in brown fat with a corresponding increase in metabolism [16].

After a month of exposure to mild cold, the participants had a 42% increase in brown fat volume and a 10% increase in fat metabolism [16].

Cold also stimulates the thyroid hormone cascade, which are hormones that cause weight loss.

If you’re stumped in your weight loss efforts, take ice baths.

6) Reduce Stress

Stress is known to cause weight gain.

Stress increases cortisol and dynorphin, both of which cause weight gain [1718, 1920].

Stress increases glutamate, which increases appetite [21].

Stress decreases NGF and BDNF, both of which are appetite suppressors.

Stress will make our brains more serotonin resistant [22] and serotonin suppresses appetite in our brains [23].

Stress also causes resistance to dopamine, which may cause us to eat more, as we’ll need to eat more food for the same rewarding effects [24].

Palatable foods really do ease the edge when we’re feeling stressed.

7) Eat Seafood, Vegetables, Fruits, and Soup

Eat more protein (best in the form of seafood) – instead of other foods.

Studies on high protein diets show that they increase fat burning, reduce appetite and lead to automatic weight loss [25, 26, 27].

Consume more fish, seafood, vegetables, fruits and seeds like chia and flax, which have lots of soluble and insoluble fiber- instead of other foods, not in addition to.

In young, overweight men, the inclusion of either lean or fatty fish, or fish oil as part of an energy-restricted diet resulted in approximately 1 kg (2.2 pounds) more weight loss after 4 weeks, than did a similar diet without seafood or a supplement [28].

Vegetables are rich in soluble fiber, which has been shown to cause weight loss in some studies [29, 30, 31]. Fiber gets broken down by bacteria in the digestive tract to produce butyrate, which has weight loss effects in animals [32].

Fruits are good, too. In a study of 91 obese individuals, eating half a fresh grapefruit before meals caused weight loss of 3.5 pounds (1.6 kg) over a period of 12 weeks [33].

Studies consistently show that dieters who eat less energy dense foods lose more weight than those who eat foods with a high energy density [34, 35, 36].

Soups are great.  Some studies have shown that eating the exact same food, except made in a soup instead of as solid food, makes people feel more satiated and eat significantly fewer calories [37, 38].

In one study, women who ate soup lost 50% more weight than women who ate an energy-dense snack [39].

Eggs over bagels: One study of 30 overweight women showed that eating eggs for breakfast, instead of bagels, increased satiety and made them eat less for the next 36 hours [40].

Reduce carbs: Carbs increase insulin, which causes weight gain, (but also satiation in the short term).  Studies have found that a low carb diet is more effective than a low-fat diet [41].

Olive oil: An olive oil-enriched diet brought about greater weight loss than a lower-fat diet in an 8-week comparison [42]. Use olive oil INSTEAD OF, not in addition to other calories. Replace saturated fat-filled oils with olive oil (olive oil already has saturated fat).

MCT oil: Consumption of MCT oil as part of a weight-loss plan improves weight loss compared with olive oil, in an 8-week study [43].

This is why I recommend Caprylic acid oil.

8) Exercise

Do high-intensity exercise, which is probably the best. Norepinephrine suppresses food intake [44].

Exercise also increases endorphins, which activate mu-opioid receptors. This suppresses appetite [45]. See a whole list of ways to naturally activate opioids.

Any exercise is good, though. Aerobic exercise (like walking, running, swimming, etc) has been shown to cause major reductions in belly fat in some studies [46, 47].

The bottom line is you need to move.

Stand, get a Treadmill Desk, bike to work, do yoga, mix it up. This is will burn calorie and increase BDNF, which causes us to eat less [48].

9) Do Yoga

Though the reason is not known, yoga can be a useful tool for weight loss [49, 50, 51].

10) Love and Be Playful

Oxytocin is released by positive human interactions and it decreases hunger [52].

Love also increases NGF [53], which reduces appetite. It also increases endorphins, which activate mu-opioid receptors.

11) Be Passionate

Be passionate about your work and life. When you’re bored, you will overeat. When you’re consumed or really busy, food is the last thing on your mind and you forget to eat.

12) Be Mindful and Meditate

If you are mindful of your food, you will eat less of it and enjoy it more.

Meditation will allow you to be less impulsive.

13) Drink Water

Drink a lot of water – Molecular Hydrogen water is better [54]. Hydrogen water increases FGF21, which results in the burning of brown fat [55].

See: Water Drinking Induces Thermogenesis through Osmosensitive Mechanisms.

Researchers have estimated that 2 liters (68 oz) of water per day can make you burn an additional 96 calories [56].

The graph below shows how drinking 500 ml (17 oz) of water can boost metabolism by 24 – 30% over a period of 1 to 1.5 hours.

14) Chew / Eat More Slowly

If you chew your food well, you will eat less of it, enjoy it more and release more satiating hormones.

Eating slowly led to decreases in energy intake within meals in healthy women.

People who were instructed to eat more slowly ended up eating 67 fewer calories during a meal. They also enjoyed their meal more.

15) Prevent Hypoglycemia

Prevent hypoglycemia or low blood glucose – mainly through a healthy diet, with lots of veggies and fruits (fiber), a good amount of protein, and a decent amount of fat (but not too much).

Hypoglycemia increases glutamate release, which increases appetite [21]. Hence, I have clients who claim to have a voracious appetite, and I already know that they’ve got excess glutamate. Hypoglycemia and stress are the most important causes of excess glutamate.

16) Lower Carb Intake

Insulin is one of the big four fattening hormones. High glycemic index carbs will cause insulin spikes and insulin resistance.

Lower carb intake in general if you’re having a problem with weight loss. My suggestion is to either go ketogenic or aim for 150g of carbs, spaced out throughout the day.

Also consume your carbs around the time you are exercising and towards the evening, when you’re more insulin sensitive (but not after your 12-hour window).

If you have high insulin, lowering carbs is certainly more important.

17) Intermittent Fasting

Fast intermittently if you’re still having problems losing weight.

Results of one of the best studies we have of intermittent fasting in humans showed that fasting every other day for 12 weeks caused 32 people to lose an average of 12 pounds more than those who followed a daily program of calorie restriction.

These people ate 25% of their calories every other day [57].

18) Take Care of Your Vagus Nerve

Increase your vagus nerve activity and oxygen through breathing exercises. Obese people have decreased heart rate variability and therefore vagal tone [58].

19) Stay Away From Junk Food

Stay away from MSG [21], artificial sweeteners and junk food.

MSG has the capacity to increase appetite [21].

20) Breath In More Oxygen By Being Outside More

A paper published in Nature provides some evidence that elevated CO2 is one cause of obesity [59].

Coinciding with the increase in obesity, atmospheric CO2 concentration has increased by more than 40% [59].

Furthermore, in modern societies, we spend more time indoors, where CO2 often reaches even higher concentrations [59].

Increased CO2 concentration in inhaled air decreases the pH of blood, which in turn spills over to cerebrospinal fluids. Nerve cells in the hypothalamus that regulate appetite and wakefulness have been shown to be extremely sensitive to pH, doubling their activity if pH decreases by 0.1 units [59].

The study hypothesizes that an increased acidic load from atmospheric CO2 may potentially lead to increased appetite and energy intake, and decreased energy expenditure, and thereby contribute to the current obesity epidemic [59].

21) Optimize Your Hormones

Make sure your levels of free and total T3, your growth hormone, and your testosterone and estrogen are ideal. Testosterone has massive effects on weight loss in men, and most men are deficient. Put LLLT on your testes for a few minutes every other day [60].

If you’re a woman with low estrogen (usually post-menopausal), estrogen replacement can help [61].

Growth hormone or GHRH (its precursor) increases muscle and decreases fat. It will help your sleep, too. Low-dose growth hormone treatment with diet restriction accelerates body fat loss and increases muscle [62].

Oxytocin [52], MSH [63] and TRH will reduce your hunger levels. Having positive relationships, sun and cold will optimize these 3 hormones. You can also buy them: TRH, MSH and Oxytocin spray.

Put LLLT on your thyroid for a few minutes every other day if your thyroid hormones are low.

Keeping to a circadian rhythm is important for balancing all of your hormones.

Synthetic birth control hormones can cause you to gain weight (up to 2kg), so be careful of those. They will increase fat and decrease muscle [64].

22) Get a Sauna

Saunas can increase weight loss, mainly in overweight people [65].

Saunas have been important for pretty much EVERY culture in the past few thousand years.

I have an infrared sauna.

23) Include These Functional Foods That Can Aid Weight Loss

  • Apple Cider Vinegar (Acetate results in appetite suppression) [66]
  • Chili/Cayenne/Sriracha – capsaicin causes weight loss [67] – in part by increasing expenditure, reducing appetite and also causing vagus nerve blocking, which reduces excess weight [68, 69, 70]
  • Dark Chocolate [71]
  • Caprylic acid (instead of other oils not in addition to)

24) Supplement Right

  • Probiotics (L gasseri, L. rhamnosus, and B lactis) [72] can help decrease intestinal inflammation, which can be a cause of weight gain [73].
  • Berberine – obese people lost an average of 5 pounds in 12 weeks [74]. Berberine induces the development of brown fat and increases UCP1 and other thermogenic genes in white and brown fat. It works via AMPK and PGC-1α. Berberine also inhibits AMPK activity in the hypothalamus.
  • HMB increases muscle mass and fat loss [75].
  • EGCG/Tea (Jasmine) causes an average weight loss of 0.2 to 3.5kg with supplements [76, 77]. EGCG inhibits MAO B, which results in weight loss [44]. Green tea can make us burn more calories, even at rest. In most studies, this amounts to about a 3 – 4% increase, although some studies show an increase as high as 8% [78, 79, 80]. For 2,000 calories, 3 – 4% amounts to an additional 60 – 80 calories per day. In one study of 60 obese individuals, the group taking green tea extract lost 7.3 lbs (3.3 kg) and burned 183 more calories per day after 3 months [81]. Results may depend on the individual [82].
  • Glucomannan [83] induced body weight reduction in healthy overweight subjects eating a healthy diet, whereas the addition of guar gum and alginate did not seem to cause additional loss of weight to a healthy diet.
  • Forskolin decreases body fat in men [84] and mitigated body fat gains in women [85] in a small study.
  • CLA (small effect) – In a review of 18 different studies, CLA caused weight loss of about 0.2 pounds (0.1 kg) per week, for up to 6 months [86]. Another review study found an average of 3 pounds (1.3 kg) of weight loss compared to placebo [87].
  • Calcium – Increasing dietary calcium significantly caused weight and fat loss and increased the percentage of fat lost from the trunk region [88]. In animals, calcium-stimulated fat tissue uncoupling protein UCP2 and muscle UCP3 and slightly increased core temperature. Calcium increased fat busting/lipolysis, decreased fatty acid synthesis, and reduced fat regains [89]. If you don’t eat dairy or sardines daily, YOU WILL BE DEFICIENT in calcium. Take with K2 and D3 to prevent build up in your arteries.
  • Green Coffee Extract/Chlorogenic acid/Kidney Bean Ext – a meta analyses found that green coffee extract results in weight loss of about 2.5kg or 5.5 pounds [90]. Kidney bean extract blocks carb absorption, which is a useful mechanism by which people can lose some weight [91].
  • Mucuna to increase dopamine, if you’ve got low levels. It might, theoretically, combat appetite. People with genetically fewer dopamine D2 receptors needed to consume more of a rewarding substance (such as drugs or food) to get that same effect. Manipulating dopamine levels altered eating behavior [24]. For example, AA or AG of rs1800497, which is a DRD2 gene (I’m AG) is associated with less pleasure and a higher risk of obesity [92].
  • Garcinia – A 2011 review that looked at 12 studies on garcinia cambogia found that, on average, it caused weight loss of about 2 pounds (0.88 kg) over several weeks [93].
  • Synephrine/Bitter orange shares similar mechanisms with ephedrine, but is less potent. It can reduce appetite and significantly increase fat burning [94].
  • Meratrim – After 8 weeks, the Meratrim group had lost 11 pounds (5.2 kg) of weight and 4.7 inches (11.9 cm) off their waistlines [95].
  • PRP – in a gene expression analysis, it was predicted that PRP can help combat obesity [96].
  • Cissus Quadrangularis [97]

25) Relatively Safe Drugs to Think About

  • Nicotine – by far your best option. Nicotine reduces appetite by activating nicotinic receptors in the lateral hypothalamus [98].
  • Caffeine [99100]
  • Metformin – metformin decreases food consumption and induces weight loss in obese people with type 2 diabetes [101].
  • Ephedrine (be careful – not safe when overdone).

Others, not recommended:

Amphetamines [44], MAO Inhibitors [44].

An SNRI (a serotonin and norepinephrine reuptake inhibitor) called sibutramine results in weight loss, which can be caused by increase serotonin and norepinephrine [102]. This drug was withdrawn because of safety issues.

Chronic inflammation, poor circadian rhythm, and stress can cause weight gain that is difficult to lose. Want to learn how I tackle these issues? Check out SelfHacked Secrets.

About the Author

Joe Cohen, BS

Joe Cohen won the genetic lottery of bad genes. As a kid, he suffered from inflammation, brain fog, fatigue, digestive problems, anxiety, depression, and other issues that were poorly understood in both conventional and alternative medicine.Frustrated by the lack of good information and tools, Joe decided to embark on a journey of self-experimentation and self-learning to improve his health--something that has since become known as “biohacking”. With thousands of experiments and pubmed articles under his belt, Joe founded SelfHacked, the resource that was missing when he needed it. SelfHacked now gets millions of monthly readers.Joe is a thriving entrepreneur, author and speaker. He is the CEO of SelfHacked, SelfDecode and LabTestAnalyzer.His mission is to help people gain access to the most up-to-date, unbiased, and science-based ways to optimize their health.
Joe has been studying health sciences for 17 years and has read over 30,000 PubMed articles. He's given consultations to over 1000 people who have sought his health advice. After completing the pre-med requirements at university, he founded SelfHacked because he wanted to make a big impact in improving global health. He's written hundreds of science posts, multiple books on improving health, and speaks at various health conferences. He's keen on building a brain-trust of top scientists who will improve the level of accuracy of health content on the web. He's also founded SelfDecode and LabTestAnalyzer, popular genetic and lab software tools to improve health.

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