In this post discussing PMID 3668686, it's clear that a diet that is overall low in protein promotes BAT. Here is another study  showing even more directly that a low-protein diet stimulates BAT activity and energy expenditure. In my last post, I pointed to evidence that the amino acid arginine appear to boost the amount of brown fat activity. But what about the mother of all protein-related, longevity-promoting dietary interventions - methionine restriction (MR)? Could the benefits of MR have something to do with BAT? Let's find out...
The two most cited studies documenting the longevity benefits of MR are this study  of rats and this study  of mice. Below are the survival curves of MR rats (left) and mice (right) from the two studies:
In rats, MR resulted in an mean lifespan extension of 20%, and a maximum lifespan extension of 12%. In fact, MR is one of the very few interventions that has ever been shown to increase max-lifespan. A fact I didn't know is that the MR rats ate more calories (after normalizing for body weight), but weighed less, than controls. Here is the body weight (left), absolute food intake (middle) and BW-normalized food intake (right) for MR rats (triangles) vs. control rats (circles).
As you can see, the MR rats gained no weight, and weighed significantly less than the control rats, despite eating nearly as much absolutely, and significantly more than controls once adjusted for body weight. The mice in  were similar in this regard to the rats in . Namely:
Mice given the control diet consumed an average of 3.8 ± 0.7 g day−1 (mean ± SD), as compared with 4.3 ± 1.1 g day−1 for mice receiving the [methionine-] restricted diet. These data provide no evidence for the idea that the low-methionine food is less palatable than the control diet. ... the data are consistent with previous reports, from rat studies, that animals on the low-methionine diet consume at least as much food per gram body weight as controls.
Despite consuming more food, the MR mice in  also weighed significantly less than controls as you can see from this diagram:
Hmmm.... increased food consumption without weight gain, resulting in increased longevity. You should know by now where this is headed...
Yup - you guessed it. Methionine restriction is yet one more way to increase BAT, as evidenced by  and . Focusing on , researchers studied MR rats vs. controls. Again the MR rats ate more for their size, but weighed less than controls. The MR rats were not thinner because of increased voluntary activity:
[There was] no evidence that the higher [energy expenditure] in MR rats was attributable to increased voluntary activity at night. In addition, ambulatory activity of the MR group during the day was significantly lower than that of the control group.
But the MR mice did have a higher core body temperature (by about 2°F!) which explains their increased energy expenditure and their low weight despite eating more. And the cause of this increase in core body temperature in the MR rats? Increased BAT activity, as is evidenced by this graph of uncoupling protein-1 expression in BAT, a marker for BAT thermogenic activity :
In support of UCP1's importance in the metabolic impact of MR, study  of mice lacking UCP1 found:
MR increased [energy expenditure] by 31% and reduced adiposity by 25% in [normal] mice. In contrast, MR failed to increase [energy expenditure] or reduce adiposity in [UCP1-knockout] mice.
Interestingly, MR appears to 'work its magic' through increased expression of FGF21 . This is interesting, because in this post we saw that mice genetically engineered to overexpress FGF21 ate more, weighed less, and live longer than control mice, just like the MR mice. And we've also seen cold exposure elevates FGF21 in rodents and people (PMID: 23150685). So it appears MR and cold exposure have similar influences on the body, and both act through upregulation of FGF21.
In summary, a (perhaps the) major physiological change resulting from methionine restriction is an increase in BAT activity via UCP1, which results in higher energy expenditure & food intake, but no increase in body weight. And of course, we know that methionine restriction results in increased lifespan. The evidence that methionine restriction promotes health and longevity via increased BAT activity would seem to put to rest any lingering doubts anyone might still harbor about the potential benefits of BAT and cold exposure.
Here is the latest full list of modifiable and [non-modifiable] factors associated with increased BAT quantity and/or activity:
- Cold exposure - by far the best BAT inducer/activator
- Methionine restriction - Reduce animal protein. Soy is low in methionine and high in arginine (see below).
- Spicy / pungent foods, herbs & supplements - capsaicin / chilli peppers, curcumin / turmeric root, menthol/mint/camphor, oregano, cloves, mustard, horseradish/wasabi, garlic, onions
- Arginine-rich foods - Good vegan sources include seeds (esp. sesame, sunflower & pumpkin), nuts (esp. almonds and walnuts) and legumes (esp. soy, lupin & fava beans and peas)
- Other foods - green tea, roasted coffee, cacao beans / chocolate
- Drugs - metformin, caffeine
- Low protein diet
- Avoid obesity/overweight
- [Being naturally thin - high metabolic rate]
- [Being younger]
- [Being female]
- [Ethnicity - having cold-climate ancestors]
 Nutrition. 2009 Nov-Dec;25(11-12):1186-92. doi: 10.1016/j.nut.2009.03.011. Epub
2009 Jun 17.
Low protein diet changes the energetic balance and sympathetic activity in brown
adipose tissue of growing rats.
Aparecida de França S(1), Dos Santos MP, Garófalo MA, Navegantes LC, Kettelhut
Ido C, Lopes CF, Kawashita NH.
(1)Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Mato
OBJECTIVE: The aim of this study was to assess the effects of protein restriction
in growing rats.
METHODS: Rats (approximate weight, 100g) were maintained with low-protein (LP;
6%) or normoproteic (control; 17%) diets, and at the end of the 15th day,
hormonal and biochemistry parameters and energetic balance were evaluated. Data
were analyzed using Student's t test (with statistical significance set at P < or
RESULTS: LP animals were hyperphagic and showed increased energetic gain (24%)
and energy expenditure (EE) compared with controls. The increase in EE was
followed by increased sympathetic activity in brown adipose tissue, evidenced by
increased norepinephrine turnover, suggesting increased thermogenesis. In spite
of hyperphagia, protein ingestion in LP animals was lower than that of controls
(P<0.01). The LP diet impaired body growth and caused deep alterations in body
chemical composition, with an increase in carcass lipid content (64%) and
reductions of protein and water. In LP animals, postprandial glycemia was
unchanged, and insulinemia was lower than in controls (P < or = .01). Reduction
in fasting glycemia without changes in insulinemia also was detected (P < .01),
suggesting increased insulin sensitivity. The LP diet caused a 100% increase in
serum leptin (P < .01).
CONCLUSIONS: Protein restriction led to an increase in EE, with probable
activation of thermogenesis in brown adipose tissue, evidenced by an increase in
catecholamines levels. Despite the higher EE, energetic gain and lipids
increased. The high level of leptin associated with hyperphagia led to the
supposition that these animals are leptin resistant, and the increase in insulin
sensitivity, suggested by the relation between insulin and glycemia in fasting
and fed animals, might contribute to lipid accumulation.
 J Nutr. 1993 Feb;123(2):269-74.
Low methionine ingestion by rats extends life span.
Orentreich N(1), Matias JR, DeFelice A, Zimmerman JA.
(1)Orentreich Foundation for the Advancement of Science, Inc., Biomedical
Research Station, Cold Spring-on-Hudson, NY 10516.
Dietary energy restriction has been a widely used means of experimentally
extending mammalian life span. We report here that lifelong reduction in the
concentration of a single dietary component, the essential amino acid
L-methionine, from 0.86 to 0.17% of the diet results in a 30% longer life span of
male Fischer 344 rats. Methionine restriction completely abolished growth,
although food intake was actually greater on a body weight basis. Studies of
energy consumption in early life indicated that the energy intake of 0.17%
methionine-fed animals was near normal for animals of their size, although
consumption per animal was below that of the much larger 0.86% methionine-fed
rats. Increasing the energy intake of rats fed 0.17% methionine failed to
increase their rate of growth, whereas restricting 0.85% methionine-fed rats to
the food intake of 0.17% methionine-fed animals did not materially reduce growth,
indicating that food restriction was not a factor in life span extension in these
experiments. The biochemically well-defined pathways of methionine metabolism and
utilization offer the potential for uncovering the precise mechanism(s)
underlying this specific dietary restriction-related extension of life span.
 Aging Cell. 2005 Jun;4(3):119-25.
Methionine-deficient diet extends mouse lifespan, slows immune and lens aging,
alters glucose, T4, IGF-I and insulin levels, and increases hepatocyte MIF levels
and stress resistance.
Miller RA(1), Buehner G, Chang Y, Harper JM, Sigler R, Smith-Wheelock M.
(1)Department of Pathology, Geriatrics Center, University of Michigan School of
Medicine, Ann Arbor, MI 48109-0940, USA. email@example.com
A diet deficient in the amino acid methionine has previously been shown to extend
lifespan in several stocks of inbred rats. We report here that a
methionine-deficient (Meth-R) diet also increases maximal lifespan in (BALB/cJ x
C57BL/6 J)F1 mice. Compared with controls, Meth-R mice have significantly lower
levels of serum IGF-I, insulin, glucose and thyroid hormone. Meth-R mice also
have higher levels of liver mRNA for MIF (macrophage migration inhibition
factor), known to be higher in several other mouse models of extended longevity.
Meth-R mice are significantly slower to develop lens turbidity and to show
age-related changes in T-cell subsets. They are also dramatically more resistant
to oxidative liver cell injury induced by injection of toxic doses of
acetaminophen. The spectrum of terminal illnesses in the Meth-R group is similar
to that seen in control mice. Studies of the cellular and molecular biology of
methionine-deprived mice may, in parallel to studies of calorie-restricted mice,
provide insights into the way in which nutritional factors modulate longevity and
 Am J Physiol Regul Integr Comp Physiol. 2010 Sep;299(3):R740-50. doi:
10.1152/ajpregu.00838.2009. Epub 2010 Jun 16.
Role of beta-adrenergic receptors in the hyperphagic and hypermetabolic responses
to dietary methionine restriction.
Plaisance EP(1), Henagan TM, Echlin H, Boudreau A, Hill KL, Lenard NR, Hasek BE,
Orentreich N, Gettys TW.
(1)Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical
Research Center, Baton Rouge, Louisiana, USA.
Dietary methionine restriction (MR) limits fat deposition and decreases plasma
leptin, while increasing food consumption, total energy expenditure (EE), plasma
adiponectin, and expression of uncoupling protein 1 (UCP1) in brown and white
adipose tissue (BAT and WAT). beta-adrenergic receptors (beta-AR) serve as
conduits for sympathetic input to adipose tissue, but their role in mediating the
effects of MR on energy homeostasis is unclear. Energy intake, weight, and
adiposity were modestly higher in beta(3)-AR(-/-) mice on the Control diet
compared with wild-type (WT) mice, but the hyperphagic response to the MR diet
and the reduction in fat deposition did not differ between the genotypes. The
absence of beta(3)-ARs also did not diminish the ability of MR to increase total
EE and plasma adiponectin or decrease leptin mRNA, but it did block the
MR-dependent increase in UCP1 mRNA in BAT but not WAT. In a further study,
propranolol was used to antagonize remaining beta-adrenergic input (beta(1)- and
beta(2)-ARs) in beta(3)-AR(-/-) mice, and this treatment blocked >50% of the
MR-induced increase in total EE and UCP1 induction in both BAT and WAT. We
conclude that signaling through beta-adrenergic receptors is a component of the
mechanism used by dietary MR to increase EE, and that beta(1)- and beta(2)-ARs
are able to substitute for beta(3)-ARs in mediating the effect of dietary MR on
EE. These findings are consistent with the involvement of both UCP1-dependent and
-independent mechanisms in the physiological responses affecting energy balance
that are produced by dietary MR.
 Am J Physiol Regul Integr Comp Physiol. 2010 Sep;299(3):R728-39. doi:
10.1152/ajpregu.00837.2009. Epub 2010 Jun 10.
Dietary methionine restriction enhances metabolic flexibility and increases
uncoupled respiration in both fed and fasted states.
Hasek BE(1), Stewart LK, Henagan TM, Boudreau A, Lenard NR, Black C, Shin J,
Huypens P, Malloy VL, Plaisance EP, Krajcik RA, Orentreich N, Gettys TW.
(1)Laboratory of Nutrient Sensing and Adipocyte Signaling, Pennington Biomedical
Research Center, Baton Rouge, Louisiana, USA.
Dietary methionine restriction (MR) is a mimetic of chronic dietary restriction
(DR) in the sense that MR increases rodent longevity, but without food
restriction. We report here that MR also persistently increases total energy
expenditure (EE) and limits fat deposition despite increasing weight-specific
food consumption. In Fischer 344 (F344) rats consuming control or MR diets for 3,
9, and 20 mo, mean EE was 1.5-fold higher in MR vs. control rats, primarily due
to higher EE during the night at all ages. The day-to-night transition produced a
twofold higher heat increment of feeding (3.0 degrees C vs. 1.5 degrees C) in MR
vs. controls and an exaggerated increase in respiratory quotient (RQ) to values
greater than 1, indicative of the interconversion of glucose to lipid by de novo
lipogenesis. The simultaneous inhibition of glucose utilization and shift to fat
oxidation during the day was also more complete in MR (RQ approximately 0.75) vs.
controls (RQ approximately 0.85). Dietary MR produced a rapid and persistent
increase in uncoupling protein 1 expression in brown (BAT) and white adipose
tissue (WAT) in conjunction with decreased leptin and increased adiponectin
levels in serum, suggesting that remodeling of the metabolic and endocrine
function of adipose tissue may have an important role in the overall increase in
EE. We conclude that the hyperphagic response to dietary MR is matched to a
coordinated increase in uncoupled respiration, suggesting the engagement of a
nutrient-sensing mechanism, which compensates for limited methionine through
integrated effects on energy homeostasis.
 Aging Cell. 2014 Oct;13(5):817-27. doi: 10.1111/acel.12238. Epub 2014 Jun 17.
Methionine restriction restores a younger metabolic phenotype in adult mice with
alterations in fibroblast growth factor 21.
Lees EK(1), Król E, Grant L, Shearer K, Wyse C, Moncur E, Bykowska AS, Mody N,
Gettys TW, Delibegovic M.
(1)Institute of Medical Sciences, College of Life Sciences and Medicine,
University of Aberdeen, Aberdeen, AB25 2ZD, UK.
Methionine restriction (MR) decreases body weight and adiposity and improves
glucose homeostasis in rodents. Similar to caloric restriction, MR extends
lifespan, but is accompanied by increased food intake and energy expenditure.
Most studies have examined MR in young animals; therefore, the aim of this study
was to investigate the ability of MR to reverse age-induced obesity and insulin
resistance in adult animals. Male C57BL/6J mice aged 2 and 12 months old were fed
MR (0.172% methionine) or control diet (0.86% methionine) for 8 weeks or 48 h.
Food intake and whole-body physiology were assessed and serum/tissues analyzed
biochemically. Methionine restriction in 12-month-old mice completely reversed
age-induced alterations in body weight, adiposity, physical activity, and glucose
tolerance to the levels measured in healthy 2-month-old control-fed mice. This
was despite a significant increase in food intake in 12-month-old MR-fed mice.
Methionine restriction decreased hepatic lipogenic gene expression and caused a
remodeling of lipid metabolism in white adipose tissue, alongside increased
insulin-induced phosphorylation of the insulin receptor (IR) and Akt in
peripheral tissues. Mice restricted of methionine exhibited increased circulating
and hepatic gene expression levels of FGF21, phosphorylation of eIF2a, and
expression of ATF4, with a concomitant decrease in IRE1α phosphorylation.
Short-term 48-h MR treatment increased hepatic FGF21 expression/secretion and
insulin signaling and improved whole-body glucose homeostasis without affecting
body weight. Our findings suggest that MR feeding can reverse the negative
effects of aging on body mass, adiposity, and insulin resistance through an FGF21
mechanism. These findings implicate MR dietary intervention as a viable therapy
for age-induced metabolic syndrome in adult humans.
 FASEB J. 2015 Jun;29(6):2603-15. doi: 10.1096/fj.14-270348. Epub 2015 Mar 5.
UCP1 is an essential mediator of the effects of methionine restriction on energy
balance but not insulin sensitivity.
Wanders D(1), Burk DH(1), Cortez CC(1), Van NT(1), Stone KP(1), Baker M(1),
Mendoza T(1), Mynatt RL(1), Gettys TW(2).
(1)*Laboratory of Nutrient Sensing and Adipocyte Signaling, Cell Biology and
Bioimaging Core, and Gene Nutrient Interactions; Pennington Biomedical Research
Center, Baton Rouge, Louisiana, USA. (2)*Laboratory of Nutrient Sensing and
Adipocyte Signaling, Cell Biology and Bioimaging Core, and Gene Nutrient
Interactions; Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
Dietary methionine restriction (MR) by 80% increases energy expenditure (EE),
reduces adiposity, and improves insulin sensitivity. We propose that the
MR-induced increase in EE limits fat deposition by increasing sympathetic nervous
system-dependent remodeling of white adipose tissue and increasing uncoupling
protein 1 (UCP1) expression in both white and brown adipose tissue. In
independent assessments of the role of UCP1 as a mediator of MR's effects on EE
and insulin sensitivity, EE did not differ between wild-type (WT) and Ucp1(-/-)
mice on the control diet, but MR increased EE by 31% and reduced adiposity by 25%
in WT mice. In contrast, MR failed to increase EE or reduce adiposity in
Ucp1(-/-) mice. However, MR was able to increase overall insulin sensitivity by
2.2-fold in both genotypes. Housing temperatures used to minimize (28°C) or
increase (23°C) sympathetic nervous system activity revealed
temperature-independent effects of the diet on EE. Metabolomics analysis showed
that genotypic and dietary effects on white adipose tissue remodeling resulted in
profound increases in fatty acid metabolism within this tissue. These findings
establish that UCP1 is required for the MR-induced increase in EE but not insulin
sensitivity and suggest that diet-induced improvements in insulin sensitivity are
not strictly derived from dietary effects on energy balance.
PMCID: PMC4447219 [Available on 2016-06-01]
There will never be peace in the world while there are animals in our bellies.