In the following sections, we’ll outline complementary approaches that may help lose weight. The below strategies are not meant to replace your standard medical treatment. Make sure to consult with your doctor before making any significant changes to your day-to-day routine.
Research over the past few decades has recognized the importance of circadian biology in obesity. Scientists think that circadian biology may have a massive influence on energy balance and metabolism .
In lab settings, mice who ate at the wrong time (when it’s dark for humans) gained more weight, despite the absence of any significant differences in calorie intake or activity over the course of the experiment. The authors suspect that their metabolism shifted .
According to another theory, a disrupted circadian rhythm may be why shift workers seem to be at an increased risk of obesity .
Short sleep duration has been associated with weight gain in many studies. A meta-analysis of 30 studies and over 630,000 people associated short sleep duration with a 55% higher incidence of obesity in adults and 89% in children [3, 4, 5].
Researchers over the past few decades have recognized the importance of circadian biology in obesity. It turns out that circadian biology may have a massive influence on energy balance and metabolism .
What’s the best way to shirt your biological clock?
There are several other ways to improve and shift your circadian rhythm, including:
- eating earlier in the morning and restricting food at night
- getting more sunlight during the day [11, 9, 12, 13]
- avoiding bright light at night and wearing blue blocking glasses at night [14, 15, 16]
- going to bed and waking up at the same time 
You can find more information about resetting your circadian rhythm here.
Additionally, it makes the brain resistant to serotonin, a neurotransmitter that also suppresses appetite. 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 [23, 24, 25].
High-intensity exercise is probably the best strategy to lose weight. In addition to promoting fat burning, the increased norepinephrine production may suppress food intake according to a study in rats .
In one study, intense light exposure, particularly in the morning, was associated with a lower BMI independent of sleep duration and timing .
Specifically, having a majority of the average daily light exposure above 500 lux earlier in the day was associated with a lower BMI .
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. Although encouraging, more research is needed to verify the link between sunlight exposure and weight loss .
In a study of 54 healthy adults, there was a 1.28 unit increase in body mass index for every extra hour of bright light in the evening .
Studies have shown that 35% of the variance in body mass index is caused by light exposure, in particular at night .
Prolonging daily light exposure increased obesity in mice by decreasing energy expenditure (through a reduced noradrenergic activation of brown fat tissue) rather than increasing food intake or activity .
You can reduce your exposure to blue light by wearing blue-blocking glasses for four hours before going to bed, covering any electronics that emit blue or green light with black tape, and put the blinds down at night if light is coming in.
Cold exposure increases metabolism and energy expenditure as the body has to adapt and produce more heat. In a clinical trial of 50 healthy men, those exposed to a cool environment overnight had a 10% increase in metabolism after one month .
In one study, subjects exposed to cold stress had an 80% increase in their metabolisms over “warm” levels .
Cold showers are the easiest way to practice acute cold exposure year-long, regardless of your climate conditions.
Love also increases NGF, which reduces appetite, and increases endorphins, which activate mu-opioid receptors .
Getting more calories in the morning has been linked to lower odds of being overweight or obese. On the other hand, eating more during nighttime increased those odds. Plus, eating later in the day was associated with losing less weight when dieting [50, 51, 52].
In animal studies, mice who ate at the wrong time gained more weight, despite having the same calorie intake and activity over the course of the experiment .
However, you need to be careful with adding breakfast to your routine. A large meta-analysis suggests that eating breakfast regularly only helps weight loss as a part of an overall healthier and more active lifestyle. If you don’t make changes to your other meals, you’d just be adding additional calories to your diet .
Some research suggests that getting more calories from protein (as opposed to either carbohydrates or fat) may support weight loss, metabolism, and satiety. High-protein diets appeared to increase fat burning and weight loss and reduce appetite in a handful of human studies [54, 55, 56].
Intermittent fasting describes any diet in which a person eats their required caloric intake during predetermined periods of time and fasts during the remaining time. Some people choose to eat only during specific times of day (for example, between 10am and 6pm), while others choose to fast for one or two entire days per week.
Results of one study 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 .
Time-restricted feeding, a strategy in which a person only eats during a specific window of time each day, has also produced good results for weight loss. However, time-restricted feeding was not as effective as other forms of intermittent fasting, according to a meta-analysis of the practice [59, 60, 61].
Insulin is one of the big four fattening hormones. High glycemic index carbs will cause insulin spikes and insulin resistance, ultimately increasing your risk of obesity. However, they also increase satiation in the short term .
In a clinical trial on 119 overweight people, a low-carbohydrate ketogenic diet was as effective as a low-fat diet for weight loss but had the advantages that it reduced appetite and negative affect. A meta-analysis of 13 studies and over 1,500 people concluded that low-carbohydrate ketogenic diets are more effective than low-fat diets for losing weight [63, 64].
Fish is hypothesized to reduce leptin; higher leptin is associated with obesity. 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 more weight loss after 4 weeks compared to a similar diet without seafood or a supplement [65, 66].
Vegetables are rich in soluble fiber, which has been shown to cause weight loss in some studies. Fiber gets broken down by bacteria in the digestive tract to produce butyrate, which has weight loss effects in animals [67, 68, 69, 70].
The idea is that soup has a very low energy density; that is, you would have to eat much more soup by weight than other foods to get the same number of calories. In several human studies, dieters who ate less energy dense foods lost more weight than those who ate foods with a high energy density [76, 77, 78].
In one study, women who ate low energy density soup lost 50% more weight than women who ate an energy-dense snack .
In a review of 11 clinical studies, olive oil-enriched diet significantly reduced BMI and waist circumference. Unlike oil in its natural form, supplementation with capsules was not effective .
Researchers have estimated that drinking 500 ml (17 oz) of water per day can boost metabolism by 24-30% over a period of 1-1.5 hours, while 2 liters (68 oz) of water can make you burn an additional 96 calories .
Molecular hydrogen water is often claimed to be better for weight loss. In the only study carried out so far (in mice) it induced FGF21, which resulted in the burning of brown fat. Whether hydrogen water has the same effects in humans remains unknown .
When ingested orally with green tea, capsaicin reduced appetite and food intake in humans. Early research indicates that taking capsaicin as a weight loss supplement is safe, but more must be known about its effectiveness [88, 89, 90].
Cocoa contains polyphenols that are believed to promote weight gain, though clinical studies are few and far between. In one study, daily consumption of 49 grams of dark chocolate reduced the quantity of snacks eaten by adults, suggesting that cocoa might decrease appetite or cravings .
In a study in rats, those fed cocoa had less fat production in the belly .
Fiber, both from foods and supplements, is known to increase satiety after a meal and decreases subsequent hunger. Studies suggest that an additional 14 g of fiber per day is associated with a 10% lower energy intake and weight loss .
How much is 14g? To put it into perspective, in the US, the average fiber intake is around 15 g/day which is only half of the recommended amount .
In a meta-analysis of 62 trials with over 3.8k people, soluble fiber modestly but significantly improved body weight and decreased waist circumference even without calorie restriction !
Some evidence suggests that resistant starch may help promote weight loss in certain circumstances. However, the research on this topic has been broadly limited to animals.
Resistant starch may stimulate fat burning by:
- Reducing fat accumulation and increasing fat oxidation after meals .
- Forcing the body to burn fat by lowering blood glucose .
- Decreasing fat production while increasing the production of phospholipids .
Butyrate is a fatty acid produced by good bacteria in the gut. The cells of the colon wall use this compound for energy .
There is some controversy over whether increased butyrate production in the colon is protective against obesity .
In a trial of 118 overweight people, fiber supplements (which the gut flora convert to butyrate) also led to reduced body weight and BMI. Animal studies have also generally found butyrate to be protective against weight gain [108, 70].
Meanwhile, in a trial of 12 men, short-chain fatty acids (including butyrate) delivered directly into the colon increased the amount of fat being burned and energy being spent .
Short-chain fatty acids may prevent weight gain and obesity through several mechanisms, including :
- Revving up fat burning (enhancing triglyceride breakdown and fatty acid oxidation)
- Transforming fat cells into brown fats, which are more easily burned for energy 
- Promoting the generation of new mitochondria
- Inhibiting chronic inflammation
Butyrate is available as a supplement, but the best way to deliver butyrate in the colon is by feeding resistant starches to the gut flora and ensuring that the gut flora remains healthy. These bacteria are well-established contributors to human metabolism and weight .
Fermented foods are considered a good dietary source of these good bacteria .
Kimchi, a fermented cabbage product, significantly increased weight loss compared to non-fermented cabbage in a study of 22 obese adults. Participants eating kimchi also had lower fasting insulin and decreased waist-to-hip ratio (indicating fat loss in the abdomen) compared to the control group .
According to one study, women who drank boiled fenugreek seed tea were less hungry and felt more full after a meal. If these properties are borne out in future research, they could make fenugreek a useful tool for people who are trying to lose weight .
In a rat study, animals fed fenugreek seed gained less weight and had lower BMI. Their blood also had lower fat and sugar levels than the control. A similar study on mice found no change in body weight but significant improvements in cholesterol levels [118, 119].
In a clinical trial of 30 prediabetic people, the group that ate quinoa for 28 days felt full and satisfied and lost weight, compared to a control group who didn’t eat quinoa .
Berberine is an alkaloid with potent metabolic effects. People use berberine as a supplement to support weight control and glucose metabolism.
Berberine supplementation reduced BMI and enhanced leptin sensitivity in 37 patients with metabolic syndrome. In another study, it caused an average weight loss of 5 lbs (2.3 kg) and lowered blood lipids [123, 124].
According to a 2020 review of human and animal studies, berberine might contribute to weight loss by improving gut microbiota and glucose and fat metabolism .
EGCG caused between 0.2 and 3.5 kg of weight loss in limited human studies. Green tea, meanwhile, is hypothesized to make us burn more calories, even at rest. In most studies, this amounts to a modest 3-4% increase in energy, though some studies have shown an increase as high as 8%. For a 2,000 calorie diet, 3-4% amounts to an additional 60-80 calories per day [126, 127, 128, 129, 130, 131].
According to a review of 11 studies, green tea extract or EGCG can slightly improve weight loss and maintenance. However, a Cochrane database review of 14 studies regarded the change in weight as nonsignificant in most studies, so the evidence is inconclusive [134, 135].
The majority of weight loss trials used special extracts with higher concentrations of active ingredients (catechins and caffeine), compared with regular tea. Hence, it may be necessary to take an EGCG-rich green tea extract for beneficial effects .
Caffeine is a well-known metabolic booster. In 12 clinical trials on 135 people, caffeine (100-600 mg/day) increased energy use and fat burning. Paradoxically, the effects were more pronounced in lean than in overweight people. Caffeine also helped maintain weight loss in 2 long-term studies on 2,500 people [136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146].
Remember that high intake of caffeine can cause adverse effects such as insomnia, anxiety, increased heart rate, breathing rate, and blood pressure, diarrhea and increased urination, and muscle twitching .
In one clinical trial on 30 overweight and obese people, Coleus forskohlii (together with a low-calorie diet) reduced weight gain, insulin resistance, and blood cholesterol (by increasing HDL). This suggests that the intervention reduced the risk of metabolic syndrome .
Another trial on 30 obese men found a decrease in body fat, increased testosterone levels, and improved bone structure after forskolin administration. However, a trial on 32 men found that the fat-burning effect of forskolin was lower in middle-aged compared to young men [148, 150].
In another trial on 23 overweight women, C. forskohlii extract did not cause weight loss directly, but prevented weight gain and did not have the side effects of other weight-loss supplements .
Overweight women applying a cream with forskolin (both alone and in combination with yohimbine and aminophylline) on their thighs experienced local fat loss (measured as reduced thigh girth) in a small trial on 28 women. Similarly, a slimming product with forskolin and other compounds (tetrahydroxypropyl ethylenediamine, caffeine, carnitine, and retinol) reduced circumference measurement and improved tonicity in a trial on 78 women [152, 153].
L. gasseri significantly decreased BMI, abdominal visceral fat, waist and hip circumferences, and body fat mass in 210 healthy Japanese adults, with an 8.5% decline in abdominal fat area over twelve weeks. However, the authors warned that constant consumption of this probiotic may be required to maintain this effect .
L. gasseri significantly decreased body weight and visceral and subcutaneous fat areas in adults with obese tendencies .
In a clinical trial of 125 obese adults, L. rhamnosus induced weight loss, reduced fat mass, and reduced circulating leptin .
Additionally, L. rhamnosus CGMCC1.3724 improved liver parameters in a small trial of 20 obese children with liver dysfunction noncompliant with lifestyle interventions .
Daily ingestion of milk containing B. animalis ssp. lactis significantly reduced the BMI, total cholesterol, low-density lipoprotein, and inflammatory markers in a clinical trial on 51 people with metabolic syndrome .
In another study of 32 obese adults, increased dietary calcium promoted weight loss and fat loss, primarily in the abdomen. Participants who ate a low-calcium diet experienced about 19% of their fat loss from the abdominal region; those who ate a high-calcium diet experienced about 50% of their fat loss from the abdomen .
However, a recent review of 41 studies concluded that calcium supplements don’t increase total weight loss .
In a trial on 200 healthy overweight people, hops extract reduced body fat, especially in the belly .
The combination of hops isohumulones and acacia proanthocyanidins improved several symptoms of metabolic syndrome. Together with diet changes and physical exercise, it decreased blood levels of triglycerides and cholesterol (total, LDL, APOB) in a trial on 23 people. The combination also reduced insulin levels while increasing insulin sensitivity in another trial on 91 people [172, 173].
In a clinical trial on 12 healthy volunteers, chlorogenic acid-enriched coffee increased weight loss by reducing sugar absorption. In another trial on 9 healthy volunteers, chlorogenic acids from coffee increased fat burning during sleep [174, 175].
Chlorogenic acid-rich coffee reduced weight and risk factors for heart disease in a clinical trial on 52 people. In those with high blood cholesterol, it also lowered blood fat (triglycerides, total cholesterol, and “bad” LDL and VLDL cholesterol) levels .
In another trial on 16 obese individuals, green coffee bean extract taken for 22 weeks reduced weight, BMI, and body fat percentage .
Both green coffee extract and a natural supplement with chlorogenic acid and several plant extracts reduced body weight and blood fat levels in 2 clinical trials on 121 people with metabolic syndrome [178, 179].
Similarly, chlorogenic acid reduced body weight, body mass index, and waist circumference in another trial on 30 people with prediabetes (impaired glucose tolerance) .
However, dark roast (low in chlorogenic acid) coffee was more effective than light roast coffee at reducing body weight in a clinical trial on 30 healthy people .
Some researchers have argued that P-synephrine may alter the function of the liver, which produces many enzymes and plays a large role in regulating digestion and energy production in the body. In animal and cell studies, it:
- Increased the breakdown of glucose and glycogen in the liver of rats and mice [183, 184, 185].
- Prevented the conversion of sugars into fats in mice .
- Increased the amount of ATP available to power chemical reactions in the liver of mice .
- Increased glucose consumption in muscle by stimulating AMPK, an enzyme that senses fuel levels in cells and stimulates the burning of fats. It also increases the intake of sugar into cells [186, 187].
- Inhibited α-amylase and α-glucosidase, enzymes that digest complex starches. This is likely to prevent post-meal blood sugar spikes .
In a clinical trial on 99 obese men, it lowered BMI and belly fat when combined with a weight-loss drug (orlistat) .
In a 2011 review of 12 studies, Garcinia extract caused a weight loss of about 2 pounds (0.88 kg) over several weeks .
Supplementation with yerba mate (3 g/day for 12 weeks) reduced body fat mass, body fat percentage, and waist-hip ratios of 30 obese participants, with no adverse side effects .
Yerba mate supplementation (1,000 mg) before exercise increased fat metabolism (fatty acid oxidation) and the energy used metabolizing the fat (crossover study with 14 healthy participants) .
In a mouse study, yerba mate supplementation decreased food intake and energy use and reduced the levels of cholesterol, triglycerides, and sugar in the blood. Additionally, it reduced the accumulation of fat in mice fed a high-fat diet .
Conjugated linoleic acids (CLA) are poly-unsaturated fatty acids. A study done in overweight Chinese subjects found that CLA supplementation (twice daily dissolved in milk) helped with weight loss over a 12-week period .
The supplementation was found to reduce body weight, reduce BMI, reduce total fat mass, and reduce fat percentage .
The treatment also reduced waist to hip ratio and reduced subcutaneous fat mass .
Studies have shown that CLAs decrease lipid storage by increasing the rate of fat breakdown in fat tissue .
- PRP 
- Cissus Quadrangularis 
- Lipoic acid 
- Carvacrol 
- I3C ameliorated 
- L-Arginine and L–Citrulline 
- Histidine [110, 111].
Metformin decreased food consumption and induced weight loss in a clinical trial on 12 obese women with type 2 diabetes. Metformin may help you lose weight if you have type 2 diabetes and your doctor prescribes you this medication. You may discuss with your doctor if it may be recommended in your case .