Scientists had previously observed that cinnamaldehyde, an essential oil that gives cinnamon its flavour, appeared to protect mice against obesity and hyperglycaemia. But the mechanisms underlying the effect were not well understood.

Researchers from the University of Michigan Life Sciences Institute wanted to better understand cinnamaldehyde’s action and determine whether it might be protective in humans, too.

Their findings, published in the journal Metabolism, suggest that cinnamaldehyde improves metabolic health by acting directly on fat cells, or adipocytes, inducing them to start burning energy through a process called thermogenesis.

The scientists tested human adipocytes from volunteers representing a range of ages, ethnicities and body mass indices. When the cells were treated with cinnamaldehyde, the researchers noticed increased activity of several genes and enzymes that enhance lipid metabolism. They also observed an increase in the proteins Ucp1 and Fgf21, which have a key role in thermogenesis.

Turning up the heat

Adipocytes normally store energy in the form of lipids. This long-term storage was beneficial to our distant ancestors, who had much less access to high-fat foods and thus a much greater need to store fat. That fat could then be used by the body in times of scarcity or in cold temperatures, which induce adipocytes to convert stored energy into heat.

“It’s only been relatively recently that energy surplus has become a problem,” said lead researchers, Jun Wu an assistant professor of molecular and integrative physiology at the University of Michigan Medical School. “Throughout evolution, the opposite – energy deficiency – has been the problem. So any energy-consuming process usually turns off the moment the body doesn’t need it.”

With the rising obesity epidemic, researchers like Wu have been looking for ways to prompt fat cells to activate thermogenesis, turning those fat-burning processes back on.

University of Warwick scientists have identified key brain cells which control our appetite – and the foods that help them do their job.

According to lead researcher Professor Nicholas Dale, tanycytes – cells found in part of the brain that controls energy levels – detect nutrients in food and tell the brain directly about the food we have eaten.

According to the new data, tanycytes in the brain respond to amino acids found in foods, via the same receptors that sense the flavour of amino acids (commonly known as “umami” taste), which are found in the taste buds of the tongue.

Two amino acids that react most with tanycytes – and therefore are likely to make you feel fuller – are arginine and lysine.

Protein-rich foods

These amino acids are found in high concentration in protein-rich animal products, fruits, vegetables, grains, nuts and seeds, such as:

• Almonds
• Anchovies
• Apricots
• Aubergines
• Avocados
• Cheese (especially parmesan)
• Chicken
• Crab
• Dates
• Figs
• Lentils
• Mackerel
• Tuna
• Turkey
• Peanuts
• Pistachios
• Plums
• Pork shoulder
• Sesame seeds
• Sweet potatoes
• Tahini (sesame seed paste)
• Walnuts

Other foods may feel just as filling when you eat them, but the key brain cells won’t be stimulated in the same way.

In contract eating these foods, according to the study published in the journal Molecular Metabolism, will activate the tanycytes and make you feel fuller and more satisfied, more quickly. This is because protein is digested more slowly and does not cause the rise in blood sugar which makes us crave more food soon after finishing a meal.

But even is these amino acids bypass the digestive system they still work their magic on the brain.

In the current study scientists found that brain cells reacted to the amino acids from these foods within 30 seconds, sending chemical signals which would travel to the part of the brain controlling appetite and body weight.

Significant implications

Dale, who is a Ted Pridgeon Professor of Neuroscience at the University of Warwick, comments:

“Amino acid levels in blood and brain following a meal are a very important signal that imparts the sensation of feeling full. Finding that tanycytes, located at the centre of the brain region that controls body weight, directly sense amino acids has very significant implications for coming up with new ways to help people to control their body weight within healthy bounds.”

Excess weight elevates the risk of premature death and a range of illnesses, such as cancer, diabetes, cardiovascular disease and stroke, which greatly reduce quality of life.

The findings which suggest the natural effect of amino acids in the foods we already eat, raise the possibility of future diet plans which could suppress the appetite and help people lose weight.

The small pilot study published in the Journal of Clinical Endocrinology and Metabolism involved 20 obese children who were randomly given a mixed carotenoid supplement (CarotenALL) or placebo for six months.

The supplement contained 600 micrograms of beta-carotene, 500 micrograms of alpha-carotene (EVTene, ExcelVite), 10 milligrams of lutein, 2 milligrams of zeaxanthin, 10 milligrams of lycopene (Lyc-O-Mato, Lycored), 500 micrograms of astaxanthin, and 10mg gamma-tocopherol (a form of vitamin E) per capsule.

At the beginning of the study researchers measured the children’s beta-carotene levels, abdominal subcutaneous and visceral fat, BMI percentile, waist-to-height ratio, and levels of the hormone adiponectin (which is made by fat cells and helps regulate metabolism).

Some nutritionists believe that deficiencies in some nutrients can contribute to weight gain. Low levels of vitamin D, for example, have been shown to correlate with obesity in children. Interestingly, these tests showed a correlation between low levels of carotenoids in the children’s blood and obesity.

Improvements across the board

By the end of the study, the children who had been taking the supplement showed improvements on several fronts.

Children taking the mixed-carotenoid supplement had an average drop of 0.19 in their BMI percentile, as well as a reduction in waist-to-height ratio, and a 4% decrease in subcutaneous abdominal fat. In the children taking the placebo subcutaneous abdominal fat actually increased by 4.2%.

In addition, after six months, adiponectin levels increased by 23% more in the supplemented children than in the children receiving a placebo.

This is important because low levels of adiponectin have been associated with obesity, insulin resistance, diabetes, and cardiovascular disease.

While this research suggests that supplementing with carotenoids might help children struggling with obesity, more research is needed to understand whether the effects seen in this study hold true over the longer term.

Some children’s supplements may contain mixed carotenoids. But kids can also get plenty of carotenoids and other important nutrients from eating a diverse diet full of colourful foods. Pink and red seafood like salmon and shrimp, for example, contain astaxanthin. Dark green, orange, red, and yellow fruits and vegetables are rich in the rest of the carotenoids in this study.

Excessive weight gain is a factor in many chronic and acute diseases, ranging from type-2 diabetes and congestive heart failure to arthritis, gastrointestinal disease, and several types of cancer,

Baobab (Adansonia digitata) is a unique tree native to Sub-Saharan Africa. The tree’s fruits are polyphenol-rich and consist of about 44% soluble and insoluble dietary fibres.

Both polyphenols and dietary fibre have been shown to increase feelings of satiety, potentially reducing hunger, and are thus of interest in alternative weight-control approaches.

Breakfast smoothie

For this study, researchers from the Functional Food Centre of Oxford Brookes University in the UK compared the effects of consuming 15 g of baobab fruit powder in a breakfast smoothie with those of consuming a control smoothie.

The 20 participants were 18-40 years of age, had a body mass index [BMI] 18-30 kg/m², (an indication of being overweight) but were otherwise healthy.

The control drink consisted of 327 mL orange juice and 100 g frozen mango; the test smoothie had the same amount of mango, 300 mL orange juice, and 15 g baobab fruit powder. Both the control and test smoothies contained 44.2 g carbohydrates, although they differed in other parameters. For example:

• The test smoothie contained 1914 μg/mL polyphenols, 3.55 g of protein, 11.9 g of fibre, 172 mg of vitamin C, and 227.5 kcal.
• The control drink contained 776 μg/mL polyphenols, 1.6 g of protein, 2.6 g of fibre, 135.1 mg of vitamin C and 213.8 kcal

The study was a crossover design, which meant that participants were given the test drink and control drinks at different points during the study period.

Each breakfast smoothie was additionally followed by 250ml of water.

Feeling less hungry

Two hours after each smoothie was consumed, participants were allowed to eat as much as they liked of a meal made up of pre-selected sandwiches, all of which were matched for calories.

There were no significant differences in energy intake or total carbohydrate, fat, or protein consumed in the sandwich meals consumed after the test smoothie and the control drink. But, say the researchers, previous studies show that people tend to eat more – ignoring the body’s satiety signals – when a meal is free. This may have influenced food intake.

On the other hands those consuming the baobab smoothie, did reported being more full, which could translate into eating less under real world conditions.

The significant reduction in hunger after drinking the baobab smoothie may have been due to delayed gastric emptying of this fibre-rich product. Polyphenols in the test drink may also have reduced glycaemic response; foods with a lower glycaemic index are associated with greater satiety.

According to the researchers, these results suggest that there should be more research on baobab’s effects on hunger and weight maintenance should be pursued.

• For more information about baobab see our article Baobab – a superfood from the ‘tree of life’

In a laboratory study researchers from the Duke University in the US have found that hormone-disrupting chemicals commonly found in house dust can trigger fat cells to accumulate more fat.

Hormone disrupting chemicals, also known as endocrine-disrupting chemicals, or EDCs, are substances that can interfere with or mimic the body’s hormones. EDCs, such as flame retardants, phthalates and bisphenol-A, are known for their potential negative effects on reproductive, neurological and immune functions.

Animal studies also suggest that early life exposure to some EDCs can cause weight gain later in life, and, as a result, have been called “obesogens” or “chemical calories”.

Some manufacturers have reduced the use of EDCs in products, but many are still ubiquitous in consumer goods. These wind up in indoor dust that can be inhaled, ingested, or absorbed through the skin.

Helping fat cell to grow

Concerned about the potential effects EDCs in dust might have on children’s health, researcher Heather Stapleton and colleagues wanted to see if the compounds in house dust might have an effect on fat cells.

The researchers collected samples of indoor dust from 11 homes in North Carolina and tested extracts from the samples in fat cells taken from mice. These types of cells are often used to test compounds for potential effects on the accumulation of triglycerides, a type of fat.

Extracts from seven of the 11 dust samples triggered the pre-adipocytes to develop into mature fat cells and accumulate triglycerides. Extracts from nine samples spurred the cells to divide, creating a larger pool of precursor fat cells. Only one dust sample had no effect.

Additionally, among the 44 individual common house dust contaminants tested in this model, the pesticides pyraclostrobin, the flame-retardant tert-butylphenyldiphenyl phosphate (TBPDP), and dibutyl phthalate (DBP), a commonly used plasticiser, had the strongest fat-producing effects.

This suggests that the mixture of these chemicals in house dust is promoting the accumulation of triglycerides and fat cells, the researchers say.

Low levels, big effects

Amounts of dust as low as 3 micrograms – well below the mass of dust the 50 milligrams that the US Environmental Protection Agency says children consume daily – caused measurable effects. This is not unexpected. Hormone-disrupting chemicals are known to produce large effects at very small doses (just as hormones in the human body do).

For this reason the researchers also suggest that house dust is a likely exposure source of chemicals that may be able to disrupt metabolic health, particularly in children.

The study results were reported in the journal Environmental Science & Technology.

• For more on this topic see our article Programmed to be Fat?
• NYR Natural News Editor Pat Thomas‘s book The 21st Century is Making You Fat, which explores chemical calories and other influences on weight gain.

The fact is there is very little human research out there to guide us, which is why a new study from China is so welcome.

Fruit and vegetables are rich sources of several biologically active components – such as polyphenols, oligosaccharides, fibre and nitrate – that contribute to general health and decrease the risk of chronic diseases such as cardiovascular disease as food for good bacterial in the gut.

The polyphenols in fruit and vegetable juices exert a variety of physiological effects including antioxidative, immunomodulatory and antimicrobial activities. They also act as food for good bacteria in the gut. The same is true for fibre.

The two most abundant bacterial in the human gut are Firmicutes (40–60%) and Bacteroidetes (20–40%) along with lower levels of Actinobacteria, Fusobacteria, Proteobacteria and Verrucomicrobia.

Recent studies show that dietary interventions with polyphenol rich extracts and foods – including dealcoholized red wine polyphenols, cocoa-derived flavanols, quercetin and grape anthocyanins – can alter this bacterial balance decreasing the abundance of Firmicutes and increasing Bifidobacteria, Lactobacillus and Verrucomicrobia, which is also a key difference in the gut microbiota between overweight and lean individuals.

Two week boost to health

For this study published in the journal Nature Scientific Reports, the scientists asked 20 healthy adults to consume only vegetable/fruit juices for 3 days followed by 14 days of customary diet.

During the intervention period all participants consumed 6 bottles of different types of vegetable/fruit juice blends daily for 3 days. The 6 different types of vegetable/fruit blends were prepared from the following fruits and vegetables:

• A green mix was blended from apple, cucumber, celery, romaine lettuce, lemon and limited amount (<2%) of spinach, kale and parsley.
• A second green mix contained added ginger.
• The root mix was a juice blend of apple, lemon, ginger and beet.
• The citrus mix contained apple, pineapple, and very limited amount (less than 1%) of lemon and mint.
• Lemon cayenne water consisted of filtered water with cayenne and lemon.
• A vanilla almond drink was made from a blend of almond, dates, sea salt and vanilla bean.

Lasting weight loss

The juice fast resulted in a significant decrease in weight and body mass index by day for and this weight loss was still evidence by day 17. Levels of nitric oxide in the blood -important for healthy arteries and blood flow – increased.

Also on day 4 the proportion of the Firmicutes and Proteobacteria in stool was significantly decreased while Bacteroidetes and Cyanobacteria had been found to increase compared to levels at the beginning of the study. However by the end of the study these had mostly reverted back to what they were at the start.

The only other human study investigating the effect of juice based diet on changes in the gut microbiota observed changes in the stool microbiome in participants following a traditional program in an Austrian Monastery including a small amount of cereal, vegetable, fruit and herbal tea.

It too found that after one week of the program an increase in microbial diversity was observed as well as the abundance of Akkermansia and Bifidobacteria was increased and the abundance of Enterobacteria and Lactobacilli was decreased.

While more research is needed, the scientists conclude that “the 3-day vegetable/fruit juice-based diet induced significant changes in the intestinal microbiota which were associated with weight loss.”

Is there a ’best juice?

In a separate study researchers, also from China, reviewed evidence for the health benefits of different juices. They found:

• Pomegranate juice was found to induce significant reductions in diastolic blood pressure (DBP) and systolic blood pressure (SBP).
• Beetroot juice had hypertensive effects and a 500ml glass could reduce blood pressure approximately three hours after ingestion.
• The juice of sweetie fruit (a hybrid between grapefruit and pomelo) had an anti-hypertensive effect, likely due to the flavonoids naringin and naritutin.
• Orange juice, cloudy apple juice and acai berry juice all have has cholesterol lowering potential, according to human studies and mulberry and blueberry juice have been found to be beneficial in this regard in animal studies.
• Plum and peach juices were found to prevent metabolic disorders induced by obesity, while plum juice could also inhibit body weight gain.

Compared to eating earlier in the day, it can increase weight, insulin and cholesterol levels, and negatively affect fat metabolism, and hormonal markers implicated in heart disease, diabetes and other health problems, according to results from researchers at the Perelman School of Medicine at the University of Pennsylvania.

The findings which were presented at the recent 31st Annual Meeting of the Associated Professional Sleep Societies, offer the first experimental evidence on the metabolic consequences of consistent delayed eating compared to daytime eating in humans.

In the study, nine healthy weight adults underwent two conditions, one of daytime eating (i.e., three meals and two snacks between 8 a.m. and 7 p.m.) for eight weeks and another of delayed eating (i.e., three meals and two snacks eating from noon to 11 p.m.) for eight weeks. There was a two-week washout period between conditions to make sure there was no carry over effect. The sleep period was held constant, between 11 p.m. to 9 a.m.

Complex measurements

Participants visited Penn’s Center for Human Phenomic Science to get metabolic measurements and have blood drawn at the beginning, after the first eating test, after the two-week washout, and after the second eating test. This allowed the research team to measure changes in weight, metabolism and energy used over the assessment period.

The team found that when participants ate later, compared to the daytime condition, weight increased. Respiratory quotient, i.e. the ratio of carbon dioxide produced by the body to oxygen consumed by the body that indicates which macronutrients are being metabolised, also rose during the delayed eating condition, indicating later eating led to metabolising fewer lipids and more carbs.

The researchers also found that a series of other measures reflecting negative metabolic profiles increased in the delayed condition, including insulin, fasting glucose, cholesterol, and triglyceride levels.

Hormone changes

Looking at a 24-hour hormonal profile, they also found that in during daytime eating condition, the hormone ghrelin, which stimulates appetite, peaked earlier in the daytime, while leptin, which keeps you satiated, peaked later, suggesting that the participants received cues to eat earlier, and eating earlier likely helped them to stay satiated longer. This suggests that eating earlier may help prevent overeating in the evening and at night. As sleep-wake cycles were constant, melatonin levels remained constant in both groups.

Similar yet much shorter previous studies have suggested similar results. For example, a study in 2009 was the first to make the link between meal timing with increased weight gain. Using mice it showed that eating at irregular times – the equivalent of the middle of the night for humans, when the body wants to sleep – directly influenced weight gain.

But this is the first long-term study looking at the timing of eating patterns that also controlled for sleep-wake cycles, exercise, macronutrient intake, etc. to pinpoint the effects of prolonged eating at different times of day.

“While lifestyle change is never easy, these findings suggest that eating earlier in the day may be worth the effort to help prevent these detrimental chronic health effects,” said Kelly Allison, PhD, an associate professor of psychology in Psychiatry and director of the Center for Weight and Eating Disorders, and senior author on the study. “We have an extensive knowledge of how overeating affects health and body weight, but now we have a better understanding of how our body processes foods at different times of day over a long period of time.”

While many claim success using this method, a new study suggests it might not be the best way to go.

The study, published in the journal JAMA Internal Medicine, looked at whether alternate-day fasting was more effective for weight loss and weight maintenance compared with daily calorie restriction. The randomized clinical trial, conducted by researchers from the University of Illinois at Chicago, followed 100 metabolically healthy obese adults for a year. They were placed into three groups: an alternate-day fasting group, a calorie-restriction group, and a no-intervention control group.

Those in the alternate-fasting group consumed 25% of their typical calorie intake (about 500 calories) on fasting days, and 125% of their typical intake on ‘feasting’ days. The calorie-restriction group (on a traditional diet) consumed 75% of their typical caloric intake every day.

After analysing the data the authors discovered that, contrary to expectations, alternate-day fasting diet was not superior to the daily calorie-restriction diet with regard to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease including blood pressure, cholesterol and glucose levels.

Both groups did lose weight, with a 6% loss for the alternate-day fasting group and a 5.3% loss for the daily calorie-restriction group. As far as regaining the weight, the researchers determined that, after 6 months of follow up, there was not a significant difference between the two groups.

Dissatisfied dieters

“Alternate-day fasting has been promoted as a potentially superior alternative to daily calorie restriction under the assumption that it is easier to restrict calories every other day,” the researchers reported. “However, our data from food records, doubly labelled water, and regular weigh-ins indicate that this assumption is not the case.”

Instead they found instead was that the dropout rate in the alternate-day fasting group was higher than that of the daily calorie-restriction group (38% vs 29% – and 26% in the control group). More participants in the alternate-day fasting group also withdrew due to dissatisfaction with diet, compared with those in the daily calorie-restriction group. Some, in the alternate-day fasting group converted their diet into de facto calorie restriction as the trial progressed.

The authors concluded that “taken together, these findings suggest that alternate-day fasting may be less sustainable in the long term, compared with daily calorie restriction, for most obese individuals.”

Still many unknowns

Research into fasting is not plentiful – it’s only in the last couple of decades that it has been on scientists’ radar.

Also most studies have only followed the participants for two or three months. The current study followed participants for a year – the longest human fasting trial to date – which included 6 months of weight loss and 6 months of maintenance. Even so this still may not be long enough to demonstrate conclusively how well each approach to weight loss works.

The results according to co-author Krista Varady, a professor of nutrition at the University of Illinois Urbana-Champaign, don’t necessarily indicate that alternate day fasting doesn’t work but just that it may not be much more effective than normal dieting. Also it does not tell us, why, for example, some people get on really well with fasting while others don’t. Personality types, the amount of stress a person is under and in particular pre-existing conditions like diabetes or pre-diabetes, may be influential. Varaday and her colleagues do plan to look at fasting diets in contexts like this in future research, so watch this space.

According to researchers from the Universitat Rovira i Virgili in Tarragona, Spain copious evidence now suggests that gut inflammation is associated with, and could even lead to, altered regulation of body weight and blood sugar balance.

Inflammation in the gut makes it easier for toxins to get past the gut’s natural barrier and into the intestinal lining. From there they gain access to the circulatory system where they can cause systemic inflammation.

Their new research, published in Molecular Nutrition and Food Research, indicates that a grape seed proanthocyanidin extract (GSPE) may protect against this.

In an animal study the scientists fed 36 rats on a Western diet for 15 weeks and then divided them into one of four supplementation groups, receiving 0 mg/kg (control dose), 5 mg/kg (low dose), 25 mg/kg (medium dose) or 50 mg/kg (high dose) of GSPE for an additional three weeks.

The medium dose is one similar to the dietary proanthocyanidin intake in humans, explained the researchers, while the high dose would exceed the normal human dietary intake.

Results showed that intestinal inflammation, significantly increased in the control animals, but these increases were reduced in those receiving the grape seed supplement.

In addition, significant reductions in blood levels of reactive oxygen species (free radicals) were seen in the medium and high dose groups, compared to the control group.

Plugging the leaks

Another important finding of the study was that the GSPE also improved the permeability of the intestinal barrier making it harder for toxins to get in. This ‘leaky gut’ was, according to the study, associated with a much higher rate of overweight and higher circulating levels of triglycerides in the animals.

“…given the importance of having a healthy barrier function, dietary interventions that can modulate the intestinal permeability might afford an effective tool for the prevention and treatment of metabolic diseases associated with obesity” they said.

The researchers concluded that supplementation with grape seed proanthocyanidin extract helped correct intestinal inflammation, oxidative stress, and possibly the barrier function of the gut:

“Based on these findings, our data suggest that nutritional and/or therapeutic interventions focused on gut health and modulation of the intestinal permeability should be extensively explored in the context of obesity.”